Encoding Device, Decoding Device, Encoding Method, and Decoding Method

This is a continuation application of PCT International Application No. PCT/JP2024/023931 filed on Jul. 2, 2024, designating the United States of America, which is based on and claims priority of U.S. Provisional Ser. No. 63/525,188 filed on Jul. 6, 2023. The entire disclosures of the above-identified applications, including the specifications, drawings and claims are incorporated herein by reference in their entirety.

The present disclosure relates to, for example, an encoding device.

Patent Literature (PTL) 1 proposes a device and a method for encoding and decoding three-dimensional mesh data.

There are demands for further improvement in processing of encoding or decoding three-dimensional data. The present disclosure improves processing of encoding or decoding three-dimensional data.

An encoding device according to an aspect of the present disclosure includes: a circuit; and memory connected to the circuit, in which, in operation, the circuit: based on positions of a plurality of second vertices generated based on positions of a plurality of first vertices included in a first three-dimensional mesh frame, calculates texture coordinates indicating positions of the plurality of second vertices in a two-dimensional coordinate system; and encodes, into a bitstream, (i) position information indicating the positions of the plurality of first vertices and (ii) a texture image that is in accordance with the texture coordinates.

Note that these general or specific aspects may be implemented using a system, a device, a method, an integrated circuit, a computer program, or a non-transitory computer-readable recording medium such as a compact disc read only memory (CD-ROM), or any combination of systems, devices, methods, integrated circuits, computer programs, and recording media.

The present disclosure can contribute toward improving processing of, for example, encoding three-dimensional data.

The present disclosure relates to an encoding device, a decoding device, an encoding method, and a decoding method for texture parametrization of a three-dimensional (3D) mesh frame. Specifically, the present disclosure relates to multimedia data coding, and particularly to systems, constituent elements, and methods in multimedia data encoding and decoding. The multimedia data includes three-dimensional digital representation of any object or surface in computer graphics applications. Particularly, a static three-dimensional model and a moving (animated) three-dimensional model that are represented with meshes including triangular meshes are included. Video can also be included in the multimedia data.

With advancement in video coding technology, from H.261 and MPEG-1 to H.264/AVC (Advanced Video Coding), MPEG-LA, H.265/HEVC (High Efficiency Video Coding) and H.266/VVC (Versatile Video Codec), there remains a constant need to provide improvements and optimizations to the video coding technology to process an ever-increasing amount of digital video data in various applications. The present disclosure relates to further advancements, improvements, and optimizations in video coding.

The encoding process for position information of three-dimensional points (vertices (also referred to as vertexes)) described in each of one or more embodiments of the present disclosure can be applied to encoding of position information of three-dimensional points in point cloud compression methods such as video-based point cloud compression (V-PCC) or geometry-based point cloud compression (G-PCC).

There are demands for further improvement in processing of encoding or decoding three-dimensional data. The present disclosure improves processing of encoding or decoding three-dimensional data.

Hereinafter, aspects of the invention derived from the content of the disclosure of the present specification will be described by way of example, and advantageous effects and the like obtained from the aspects of the invention will be described.

An encoding device according to Example 1 includes a circuit and memory connected to the circuit, in which, in operation, the circuit: based on positions of a plurality of second vertices generated based on positions of a plurality of first vertices included in a first three-dimensional mesh frame, calculates texture coordinates indicating positions of the plurality of second vertices in a two-dimensional coordinate system; and encodes, into a bitstream, (i) position information indicating the positions of the plurality of first vertices and (ii) a texture image that is in accordance with the texture coordinates.

The plurality of second vertices are generated as a result of subdivision of the first three-dimensional mesh frame, for example. This makes it possible to generate a mesh frame denser than the first three-dimensional mesh frame. By calculating texture coordinates based on the mesh frame generated in such a manner, that is, by determining the texture of the mesh frame, it is possible to determine the texture coordinates more finely than in the case of calculating the texture coordinates based on the plurality of first vertices. Accordingly, defects such as application of a wrong texture or no texture to the first three-dimensional mesh frame by a decoding process or the like can be inhibited.

An encoding device according to Example 2 is the encoding device according to Example 1, in which the circuit may further generate the texture image based on the texture coordinates.

With this, only the texture image related to the calculated texture coordinates is encoded into the bitstream. Accordingly, the code amount of the bitstream is reduced.

An encoding device according to Example 3 is the encoding device according to Example 1 or 2, in which the circuit may further generate the plurality of second vertices by subdividing the first three-dimensional mesh frame.

This makes it possible to determine the texture coordinates more finely than in the case of calculating the texture coordinates based on the plurality of first vertices.

An encoding device according to Example 4 is the encoding device according to any one of Examples 1 to 3, in which the circuit may further encode, into the bitstream, first count information indicating a total number of times the first three-dimensional mesh frame is subdivided to calculate the texture coordinates.

This makes it possible to perform subdivisions the same number of times in encoding and decoding. Accordingly, the quality of the three-dimensional mesh frame reconstructed by a decoding device can be improved.

An encoding device according to Example 5 is the encoding device according to any one of Examples 1 to 4, in which the circuit may further encode, into the bitstream, second count information indicating a total number of times the first three-dimensional mesh frame is subdivided to generate a second three-dimensional mesh frame from the first three-dimensional mesh frame.

With this, for example, even when a difference exists between the total number of times the first three-dimensional mesh frame is subdivided to calculate texture coordinates and the total number of times the first three-dimensional mesh frame is subdivided to generate the second three-dimensional mesh frame from the first three-dimensional mesh frame, the encoding device and the decoding device can perform subdivisions the same number of times. Accordingly, the quality of the three-dimensional mesh frame reconstructed by the decoding device can be improved.

An encoding device according to Example 6 is the encoding device according to any one of Examples 1 to 5, in which the circuit may further: displace the plurality of second vertices; and when calculating the texture coordinates, calculate the texture coordinates based on the positions of the plurality of second vertices after displacement.

With this, even when vertices are displaced and then position information indicating the positions of the displaced vertices is encoded, the encoding device and the decoding device can calculate texture coordinates using vertices of the same positions.

An encoding device according to Example 7 is the encoding device according to any one of Examples 1 to 6, in which the circuit may encode, into the bitstream, flag information indicating whether to displace the plurality of second vertices.

This makes it possible for the decoding device to determine whether to displace vertices based on the flag information.

A decoding device according to Example 8 includes a circuit and memory connected to the circuit, in which, in operation, the circuit: decodes, from a bitstream, (i) position information indicating positions of a plurality of first vertices included in a first three-dimensional mesh frame and (ii) a texture image; and by using positions of a plurality of second vertices generated from the position information, calculates texture coordinates indicating positions of the plurality of second vertices in the texture image.

The plurality of second vertices are generated as a result of subdivision of the first three-dimensional mesh frame, for example. This makes it possible to generate a mesh frame denser than the first three-dimensional mesh frame. By calculating texture coordinates based on the mesh frame generated in such a manner, that is, by determining the texture of the mesh frame, it is possible to determine the texture coordinates more finely than in the case of calculating the texture coordinates based on the plurality of first vertices. Accordingly, defects such as application of a wrong texture or no texture to the first three-dimensional mesh frame by a decoding process or the like can be inhibited.

A decoding device according to Example 9 is the decoding device according to Example 8, in which the circuit may further generate the plurality of second vertices by subdividing the first three-dimensional mesh frame.

This makes it possible to determine the texture coordinates more finely than in the case of calculating the texture coordinates based on the plurality of first vertices.

A decoding device according to Example 10 is the decoding device according to Example 8 or 9, in which the circuit may further: decode, from the bitstream, first count information indicating a total number of times the first three-dimensional mesh frame is subdivided to calculate the texture coordinates; and when calculating the texture coordinates, calculate the texture coordinates using the first count information.

This makes it possible to perform subdivisions the same number of times in encoding and decoding. Accordingly, the quality of the three-dimensional mesh frame reconstructed by the decoding device can be improved.

A decoding device according to Example 11 is the decoding device according to any one of Examples 8 to 10, in which the circuit may further: decode, from the bitstream, second count information indicating a total number of times the first three-dimensional mesh frame is subdivided to generate a second three-dimensional mesh frame from the first three-dimensional mesh frame; and generate the second three-dimensional mesh frame from the first three-dimensional mesh frame by using the texture coordinates and the second count information.

With this, for example, even when a difference exists between the total number of times the first three-dimensional mesh frame is subdivided to calculate texture coordinates and the total number of times the first three-dimensional mesh frame is subdivided to generate the second three-dimensional mesh frame from the first three-dimensional mesh frame, the encoding device and the decoding device can perform subdivisions the same number of times. Accordingly, the quality of the three-dimensional mesh frame reconstructed by the decoding device can be improved.

A decoding device according to Example 12 is the decoding device according to any one of Examples 8 to 11, in which the circuit may further: displace the plurality of second vertices; and when calculating the texture coordinates, calculate the texture coordinates based on the positions of the plurality of second vertices after displacement.

With this, even when vertices are displaced and then position information indicating the positions of the displaced vertices is encoded, the encoding device and the decoding device can calculate texture coordinates using vertices of the same positions.

A decoding device according to Example 13 is the decoding device according to any one of Examples 8 to 12, in which the circuit may decode, from the bitstream, flag information indicating whether to displace the plurality of second vertices.

This makes it possible for the decoding device to determine whether to displace vertices based on the flag information.

An encoding method according to Example 14 includes: based on positions of a plurality of second vertices generated based on positions of a plurality of first vertices included in a first three-dimensional mesh frame, calculating texture coordinates indicating positions of the plurality of second vertices in a two-dimensional coordinate system; and encoding, into a bitstream, (i) position information indicating the positions of the plurality of first vertices and (ii) a texture image that is in accordance with the texture coordinates.

With this, the same advantageous effects as those produced by the encoding device according to Example 1 are produced.

A decoding method according to Example 15 includes: decoding, from a bitstream, (i) position information indicating positions of a plurality of first vertices included in a first three-dimensional mesh frame and (ii) a texture image; and by using positions of a plurality of second vertices generated from the position information, calculating texture coordinates indicating positions of the plurality of second vertices in the texture image.

With this, the same advantageous effects as those produced by the decoding device according to Example 8 are produced.

Moreover, these general or specific aspects may be implemented using a system, a device, a method, an integrated circuit, a computer program, or a non-transitory computer-readable recording medium such as a CD-ROM, or any combination of systems, devices, methods, integrated circuits, computer programs, and recording media.

(1) Three-dimensional mesh The following expressions and terms will be used herein.

(2) Vertex information A three-dimensional mesh is a set of a plurality of faces and indicates, for example, a three-dimensional object. In addition, a three-dimensional mesh is mainly constituted of vertex information, connection information, and attribute information. A three-dimensional mesh may be expressed as a polygon mesh or a mesh. In addition, a three-dimensional mesh may have a temporal change. A three-dimensional mesh may include metadata related to vertex information, connection information, and attribute information, or other additional information.

(3) Connection information Vertex information is information indicating a vertex. For example, vertex information indicates a position of a vertex in a three-dimensional space. In addition, a vertex corresponds to a vertex of a face that constitutes a three-dimensional mesh. Vertex information may be expressed as “geometry”. In addition, vertex information may also be expressed as position information.

(4) Attribute information Connection information is information indicating a connection between vertexes. For example, connection information indicates a connection for constructing a face or an edge of a three-dimensional mesh. Connection information may be expressed as “connectivity”. In addition, connection information may also be expressed as face information.

(5) Face Attribute information is information indicating an attribute of a vertex or a face. For example, attribute information indicates an attribute such as a color, an image, a normal vector, and the like associated with a vertex or a face. Attribute information may be expressed as “texture”.

(6) Plane A face is an element that constitutes a three-dimensional mesh. Specifically, a face is a polygon on a plane in a three-dimensional space. For example, a face can be determined as a triangle in the three-dimensional space.

(7) Bitstream A plane is a two-dimensional plane in a three-dimensional space. For example, a polygon is formed on a plane and a plurality of polygons are formed on a plurality of planes.

(8) Encoding and decoding A bitstream corresponds to encoded information. A bitstream can also be expressed as a stream, an encoded bitstream, a compressed bitstream, or an encoded signal.

The expression “encode” may be replaced with expressions such as store, include, write, describe, signalize, send out, notify, save, or compress and such expressions may be interchangeably used. For example, encoding information may mean including information in a bitstream. In addition, encoding information in a bitstream may mean encoding the information and generating a bitstream that includes the encoded information.

(9) Ordinal numbers In addition, the expression “decode” may be replaced with expressions such as read, interpret, scan, load, derive, acquire (obtain), receive, extract, restore, reconstruct, decompress, or expand and such expressions may be interchangeably used. For example, decoding information may mean acquiring information from a bitstream. In addition, decoding information from a bitstream may mean decoding the bitstream and acquiring information included in the bitstream.

In the description, an ordinal number such as first, second, or the like may be affixed to a constituent element or the like. Such ordinal numbers may be replaced as necessary. In addition, an ordinal number may be newly affixed to or removed from a constituent element or the like. Furthermore, the ordinal numbers may be affixed to elements in order to identify the elements and may not correspond to any meaningful order.

1 FIG. is a conceptual diagram illustrating a three-dimensional mesh according to the present embodiment. The three-dimensional mesh is constituted of a plurality of faces. For example, each face is a triangle. Vertexes of the triangles are determined in a three-dimensional space. In addition, a three-dimensional mesh indicates a three-dimensional object. Each face may have a color or an image.

2 FIG. is a conceptual diagram illustrating basic elements of a three-dimensional mesh according to the present embodiment. The three-dimensional mesh is constituted of vertex information, connection information, and attribute information. Vertex information indicates a position of a vertex of a face in a three-dimensional space. Connection information indicates a connection between vertexes. A face can be identified based on vertex information and connection information. In other words, an uncolored three-dimensional object is formed in a three-dimensional space based on vertex information and connection information.

Attribute information may be associated with a vertex or associated with a face. Attribute information associated with a vertex may be expressed as “attribute per point”. Attribute information associated with a vertex may indicate an attribute of the vertex itself or indicate an attribute of a face connected to the vertex.

For example, a color may be associated with a vertex as attribute information. The color associated with the vertex may be the color of the vertex or the color of a face connected to the vertex. The color of the face may be an average of a plurality of colors associated with a plurality of vertexes of the face. In addition, a normal vector may be associated with a vertex or a face as attribute information. Such a normal vector can express a front and a rear of a face.

In addition, a two-dimensional image may be associated with a face as attribute information. The two-dimensional image associated with a face is also expressed as a texture image or an “attribute map”. In addition, information indicating mapping between a face and a two-dimensional image may be associated with the face as attribute information. Such information indicating mapping may be expressed as mapping information, vertex information of a texture image, texture coordinates, or an “attribute UV coordinate”.

Furthermore, information on a color, an image, a moving image, and the like to be used as attribute information may be expressed as “parametric space”.

A texture can be reflected in a three-dimensional object based on such attribute information. In other words, a colored three-dimensional object is formed in a three-dimensional space based on vertex information, connection information, and attribute information.

Note that while attribute information is associated with a vertex or a face in the description given above, alternatively, attribute information may be associated with an edge.

3 FIG. is a conceptual diagram illustrating mapping according to the present embodiment. For example, a region of a two-dimensional image on a two-dimensional plane can be mapped to a face of a three-dimensional mesh in a three-dimensional space. Specifically, coordinate information of a region in the two-dimensional image is associated with a face of the three-dimensional mesh. Accordingly, an image of the mapped region in the two-dimensional image is reflected in the face of the three-dimensional mesh.

With use of mapping, a two-dimensional image to be used as attribute information can be separated from the three-dimensional mesh. For example, in encoding of the three-dimensional mesh, the two-dimensional image may be encoded based on an image encoding system or a video encoding system.

4 FIG. 4 FIG. 100 200 is a block diagram illustrating a configuration example of an encoding and decoding system according to the present embodiment. In, the encoding and decoding system includes encoding deviceand decoding device.

100 100 300 For example, encoding deviceacquires a three-dimensional mesh and encodes the three-dimensional mesh into a bitstream. In addition, encoding deviceoutputs the bitstream to network. For example, the bitstream includes an encoded three-dimensional mesh and control information for decoding the encoded three-dimensional mesh. Encoding of the three-dimensional mesh causes information of the three-dimensional mesh to be compressed.

300 100 200 300 300 Networktransmits the bitstream from encoding deviceto decoding device. Networkmay be the Internet, a wide area network (WAN), a local area network (LAN), or a combination thereof. Networkis not necessarily limited to two-way communication and may be a unidirectional communication network for terrestrial digital broadcasting, satellite broadcasting, or the like.

300 In addition, networkmay be replaced with a recording medium such as a digital versatile disc (DVD), a Blu-Ray Disc (registered trademark) (BD), or the like.

200 200 100 100 200 Decoding deviceacquires a bitstream and decodes a three-dimensional mesh from the bitstream. Decoding of the three-dimensional mesh causes information of the three-dimensional mesh to be expanded. For example, decoding devicedecodes a three-dimensional mesh according to a decoding method corresponding to an encoding method used by encoding deviceto encode the three-dimensional mesh. In other words, encoding deviceand decoding deviceperform encoding and decoding according to an encoding method and a decoding method which correspond to each other.

Note that the three-dimensional mesh before encoding can also be expressed as an original three-dimensional mesh. In addition, the three-dimensional mesh after decoding is also expressed as a reconstructed three-dimensional mesh.

5 FIG. 100 100 101 102 103 is a block diagram illustrating a configuration example of encoding deviceaccording to the present embodiment. For example, encoding deviceincludes vertex information encoder, connection information encoder, and attribute information encoder.

101 101 Vertex information encoderis an electric circuit which encodes vertex information. For example, vertex information encoderencodes vertex information into a bitstream according to a format defined with respect to the vertex information.

102 102 Connection information encoderis an electric circuit which encodes connection information. For example, connection information encoderencodes connection information into a bitstream according to a format defined with respect to the connection information.

103 103 Attribute information encoderis an electric circuit which encodes attribute information. For example, attribute information encoderencodes attribute information into a bitstream according to a format defined with respect to the attribute information.

Variable-length coding or fixed length coding may be used for encoding vertex information, connection information, and attribute information. The variable-length coding may accommodate Huffman coding, context-adaptive binary arithmetic coding (CABAC), or the like.

101 102 103 101 102 103 Vertex information encoder, connection information encoder, and attribute information encodermay be integrated. Alternatively, each of vertex information encoder, connection information encoder, and attribute information encodermay be more finely segmentalized into a plurality of constituent elements.

6 FIG. 5 FIG. 100 100 104 105 is a block diagram illustrating another configuration example of encoding deviceaccording to the present embodiment. For example, in addition to the configuration illustrated in, encoding deviceincludes preprocessorand postprocessor.

104 104 104 Preprocessoris an electric circuit which performs processing before encoding of vertex information, connection information, and attribute information. For example, preprocessormay perform transformation processing, demultiplexing, multiplexing, or the like with respect to a three-dimensional mesh before encoding. More specifically, for example, preprocessormay demultiplex vertex information, connection information, and attribute information from the three-dimensional mesh before encoding.

105 105 105 105 Postprocessoris an electric circuit which performs processing after the encoding of vertex information, connection information, and attribute information. For example, postprocessormay perform transformation processing, demultiplexing, multiplexing, or the like with respect to vertex information, connection information, and attribute information after encoding. More specifically, for example, postprocessormay multiplex vertex information, connection information, and attribute information after encoding into a bitstream. In addition, for example, postprocessormay further perform variable-length coding with respect to vertex information, connection information, and attribute information after the encoding.

7 FIG. 200 200 201 202 203 is a block diagram illustrating a configuration example of decoding deviceaccording to the present embodiment. For example, decoding deviceincludes vertex information decoder, connection information decoder, and attribute information decoder.

201 201 Vertex information decoderis an electric circuit which decodes vertex information. For example, vertex information decoderdecodes vertex information from a bitstream according to a format defined with respect to the vertex information.

202 202 Connection information decoderis an electric circuit which decodes connection information. For example, connection information decoderdecodes connection information from a bitstream according to a format defined with respect to the connection information.

203 203 Attribute information decoderis an electric circuit which decodes attribute information. For example, attribute information decoderdecodes attribute information from a bitstream according to a format defined with respect to the attribute information.

Variable-length decoding or fixed length decoding may be used for decoding vertex information, connection information, and attribute information. The variable-length decoding may accommodate Huffman coding, context-adaptive binary arithmetic coding (CABAC), or the like.

201 202 203 201 202 203 Vertex information decoder, connection information decoder, and attribute information decodermay be integrated. Alternatively, each of vertex information decoder, connection information decoder, and attribute information decodermay be more finely segmentalized into a plurality of constituent elements.

8 FIG. 7 FIG. 200 200 204 205 is a block diagram illustrating another configuration example of decoding deviceaccording to the present embodiment. For example, in addition to the components illustrated in, decoding deviceincludes preprocessorand postprocessor.

204 204 Preprocessoris an electric circuit which performs processing before decoding of vertex information, connection information, and attribute information. For example, preprocessormay perform transformation processing, demultiplexing, multiplexing, or the like with respect to a bitstream before decoding of vertex information, connection information, and attribute information.

204 204 More specifically, for example, preprocessormay demultiplex, from a bitstream, a sub-bitstream corresponding to vertex information, a sub-bitstream corresponding to connection information, and a sub-bitstream corresponding to attribute information. In addition, for example, preprocessormay perform variable-length decoding with respect to the bitstream in advance before decoding of vertex information, connection information, and attribute information.

205 205 205 Postprocessoris an electric circuit which performs processing after the decoding of vertex information, connection information, and attribute information. For example, postprocessormay perform transformation processing, demultiplexing, multiplexing, or the like with respect to vertex information, connection information, and attribute information after decoding. More specifically, for example, postprocessormay multiplex vertex information, connection information, and attribute information after decoding into a three-dimensional mesh.

Vertex information, connection information, and attribute information are encoded and stored in a bitstream. A relationship between these pieces of information and the bitstream will be described below.

9 FIG. is a conceptual diagram illustrating a configuration example of a bitstream according to the present embodiment. In this example, connection information, vertex information, and attribute information are integrated in the bitstream. For example, connection information, vertex information, and attribute information may be included in one file.

In addition, a plurality of portions of the pieces of information may be sequentially stored such as a first portion of connection information, a first portion of vertex information, a first portion of attribute information, a second portion of connection information, a second portion of vertex information, a second portion of attribute information, . . . The plurality of portions may correspond to a plurality of temporally different portions, correspond to a plurality of spatially different portions, or correspond to a plurality of different faces.

Furthermore, an order of storage of connection information, vertex information, and attribute information is not limited to the example described above and an order of storage that differs from the above may be used.

10 FIG. is a conceptual diagram illustrating another configuration example of a bitstream according to the present embodiment. In the example, a plurality of files are included in a bitstream and connection information, vertex information, and attribute information are respectively stored in different files. While a file including connection information, a file including vertex information, and a file including attribute information are illustrated here, storage formats are not limited to this example. For example, two types of information among connection information, vertex information, and attribute information may be included in one file and the one remaining type of information may be included in another file.

Alternatively, the pieces of information can be stored by being divided into a larger number of files. For example, a plurality of portions of connection information may be stored in a plurality of files, a plurality of portions of vertex information may be stored in a plurality of files, and a plurality of portions of attribute information may be stored in a plurality of files. The plurality of portions may correspond to a plurality of temporally different portions, correspond to a plurality of spatially different portions, or correspond to a plurality of different faces.

Furthermore, an order of storage of connection information, vertex information, and attribute information is not limited to the example described above and an order of storage that differs from the above may be used.

11 FIG. is a conceptual diagram illustrating another configuration example of a bitstream according to the present embodiment. In the example, a bitstream is constituted of a plurality of separable sub-bitstreams and connection information, vertex information, and attribute information are respectively stored in different sub-bitstreams.

While a sub-bitstream including connection information, a sub-bitstream including vertex information, and a sub-bitstream including attribute information are illustrated here, storage formats are not limited to this example.

For example, two types of information among connection information, vertex information, and attribute information may be included in one sub-bitstream and the one remaining type of information may be included in another sub-bitstream. Specifically, attribute information such as a two-dimensional image may be stored in a sub-bitstream conforming to an image coding system separately from a sub-bitstream of connection information and vertex information.

In addition, each sub-bitstream may include a plurality of files. Furthermore, a plurality of portions of connection information may be stored in a plurality of files, a plurality of portions of vertex information may be stored in a plurality of files, and a plurality of portions of attribute information may be stored in a plurality of files.

9 FIG. 10 FIG. 11 FIG. Furthermore, an order of storage of connection information, vertex information, and attribute information is not limited to the example illustrated in,, and, and an order of storage that differs from this example may be used. For example, vertex information, connection information, and attribute information may be stored in a bitstream in this order. Alternatively, in an order other than this order, e.g., in any of orders: connection information, attribute information, and vertex information; vertex information, attribute information, and connection information; attribute information, connection information, and vertex information; and attribute information, vertex information, and connection information, these pieces of information may be stored in a bitstream.

Furthermore, each of connection information, vertex information, and attribute information may be divided into a plurality of data items, and the plurality of data items may be stored in a bitstream in a periodic order or in a random order.

12 FIG. 12 FIG. 110 210 310 is a block diagram illustrating a specific example of the encoding and decoding system according to the present embodiment. In, the encoding and decoding system includes three-dimensional data encoding system, three-dimensional data decoding system, and external connector.

110 111 112 113 115 114 210 211 212 213 214 215 216 Three-dimensional data encoding systemincludes controller, input/output processor, three-dimensional data encoder, three-dimensional data generator, and system multiplexer. Three-dimensional data decoding systemincludes controller, input/output processor, three-dimensional data decoder, system demultiplexer, presenter, and user interface.

110 115 115 113 In three-dimensional data encoding system, sensor data is input from a sensor terminal to three-dimensional data generator. Three-dimensional data generatorgenerates three-dimensional data that is point cloud data, mesh data, or the like from the sensor data and inputs the three-dimensional data to three-dimensional data encoder.

115 115 115 115 For example, three-dimensional data generatorgenerates vertex information and generates connection information and attribute information which correspond to the vertex information. Three-dimensional data generatormay process vertex information when generating connection information and attribute information. For example, three-dimensional data generatormay reduce a data amount by deleting overlapping vertexes or transform vertex information (position shift, rotation, normalization, or the like). In addition, three-dimensional data generatormay render attribute information.

115 110 115 110 12 FIG. While three-dimensional data generatoris a constituent element of three-dimensional data encoding systemin, three-dimensional data generatormay be disposed on the outside independent of three-dimensional data encoding system.

For example, a sensor terminal that provides sensor data for generating three-dimensional data may be a mobile object such as an automobile, a flying object such as an airplane, a mobile terminal, a camera, or the like. Alternatively, a range sensor such as LIDAR, a millimeter-wave radar, an infrared sensor, or a range finder, a stereo camera, a combination of a plurality of monocular cameras, or the like may be used as the sensor terminal.

The sensor data may be a distance (position) of an object, a monocular camera image, a stereo camera image, a color, a reflectance, an attitude or an orientation of a sensor, a gyro, a sensing position (GPS information or elevation), a velocity, an acceleration, a time of day of sensing, air temperature, air pressure, humidity, magnetism, or the like.

113 100 113 113 113 114 5 FIG. Three-dimensional data encodercorresponds to encoding deviceillustrated inand the like. For example, three-dimensional data encoderencodes three-dimensional data and generates encoded data. In addition, three-dimensional data encodergenerates control information when encoding the three-dimensional data. Furthermore, three-dimensional data encoderinputs the encoded data to system multiplexertogether with the control information.

The encoding system of three-dimensional data may be an encoding system using geometry or an encoding system using a video codec. In this case, an encoding system using geometry may also be expressed as a geometry-based encoding system. An encoding system using a video codec may also be expressed as a video-based encoding system.

114 113 114 114 System multiplexermultiplexes encoded data and control information input from three-dimensional data encoderand generates multiplexed data using a prescribed multiplexing system. System multiplexermay multiplex other media such as video, audio, subtitles, application data, or document files, reference time information, or the like together with the encoded data and control information of three-dimensional data. Furthermore, system multiplexermay multiplex attribute information related to sensor data or three-dimensional data.

For example, multiplexed data has a file format for accumulation, a packet format for transmission, or the like. ISOBMFF or an ISOBMFF-based system may be used as an accumulation system or a transmission system. Alternatively, MPEG-DASH, MMT, MPEG-2 TS Systems, RTP, or the like may be used.

112 310 In addition, multiplexed data is output as a transmission signal by input/output processorto external connector. The multiplexed data may be transmitted as a transmission signal in a wired manner or in a wireless manner. Alternatively, the multiplexed data is accumulated in an internal memory or a storage device. The multiplexed data may be transmitted via the Internet to a cloud server or stored in an external storage device.

For example, the transmission or accumulation of the multiplexed data is performed by a method in accordance with a medium for transmission or accumulation such as broadcasting or communication. As a communication protocol, http, ftp, TCP, UDP, IP, or a combination thereof may be used. In addition, a pull-type communication scheme may be used or a push-type communication scheme may be used.

Ethernet (registered trademark), USB, RS-232C, HDMI (registered trademark), a coaxial cable, or the like may be used for wired transmission. In addition, 3GPP (registered trademark), 3G/4G/5G as specified by IEEE, a wireless LAN, Bluetooth, or a millimeter-wave may be used for wireless transmission. Furthermore, for example, DVB-T2, DVB-S2, DVB-C2, ATSC 3.0, ISDB-S3, or the like may be used as a broadcasting system.

115 114 310 112 110 210 310 Note that sensor data may be input to three-dimensional data generatoror system multiplexer. In addition, three-dimensional data or encoded data may be output as-is as a transmission signal to external connectorvia input/output processor. The transmission signal output from three-dimensional data encoding systemis input to three-dimensional data decoding systemvia external connector.

110 111 In addition, each operation of three-dimensional data encoding systemmay be controlled by controllerwhich executes application programs.

210 212 212 214 214 213 214 In three-dimensional data decoding system, a transmission signal is input to input/output processor. Input/output processordecodes multiplexed data having a file format or a packet format from the transmission signal and inputs the multiplexed data to system demultiplexer. System demultiplexeracquires encoded data and control information from the multiplexed data and inputs the encoded data and the control information to three-dimensional data decoder. System demultiplexermay extract other media, reference time information, or the like from the multiplexed data.

213 200 213 215 7 FIG. Three-dimensional data decodercorresponds to decoding deviceillustrated inand the like. For example, three-dimensional data decoderdecodes three-dimensional data from the encoded data based on an encoding system specified in advance. Subsequently, the three-dimensional data is presented to a user by presenter.

215 215 216 215 In addition, additional information such as sensor data may be input to presenter. Presentermay present three-dimensional data based on the additional information. In addition, an instruction by the user may be input to user interfacefrom a user terminal. Furthermore, presentermay present three-dimensional data based on the input instruction.

212 310 Note that input/output processormay acquire three-dimensional data and encoded data from external connector.

210 211 In addition, each operation of three-dimensional data decoding systemmay be controlled by controllerwhich executes application programs.

13 FIG. is a conceptual diagram illustrating a configuration example of point cloud data according to the present embodiment. Point cloud data refers to data of a point cloud that indicates a three-dimensional object.

Specifically, a point cloud is constituted of a plurality of points and has position information which indicates a three-dimensional coordinate position of each point and attribute information which indicates an attribute of each point. The position information is also expressed as geometry.

For example, a type of attribute information may be a color, a reflectance, or the like. Attribute information related to one type may be associated with one point, attribute information related to a plurality of different types may be associated with one point, or attribute information having a plurality of values with respect to a same type may be associated with one point.

14 FIG. is a conceptual diagram illustrating a data file example of the point cloud data according to the present embodiment. The example is an example of a case where items of position information and items of attribute information have a one-to-one correspondence and the example indicates position information and attribute information of N-number of points which constitute the point cloud data. In this example, position information is information indicating a three-dimensional coordinate position by three axes of x, y, and z and attribute information is information indicating a color by RGB. As a representative data file of point cloud data, a PLY file or the like can be used.

15 FIG. is a conceptual diagram illustrating a configuration example of mesh data according to the present embodiment. Mesh data is data used in CG (computer graphics) or the like and is data of a three-dimensional mesh which represents a three-dimensional shape of an object by a plurality of faces. Each face is also expressed as a polygon and has a polygonal shape such as a triangle or a quadrilateral.

Specifically, in addition to the plurality of points which constitute a point cloud, a three-dimensional mesh is constituted of a plurality of edges and a plurality of faces. Each point is also expressed as a vertex or a position. Each edge corresponds to a line segment which connects two vertexes. Each face corresponds to an area enclosed by three or more edges.

In addition, a three-dimensional mesh has position information indicating three-dimensional coordinate positions of vertexes. The position information is also expressed as vertex information or geometry. Furthermore, a three-dimensional mesh has connection information indicating a relationship among a plurality of vertexes constituting an edge or a face. The connection information is also expressed as connectivity. In addition, a three-dimensional mesh has attribute information indicating an attribute with respect to a vertex, an edge, or a face. The attribute information in a three-dimensional mesh is also expressed as a texture.

For example, attribute information may indicate a color, a reflectance, or a normal vector with respect to a vertex, an edge, or a face. An orientation of a normal vector can express a front and a rear of a face.

An object file or the like may be used as a data file format of mesh data.

16 FIG. is a conceptual diagram illustrating a data file example of the mesh data according to the present embodiment. In the example, a data file includes pieces of position information G(1) to G(N) and pieces of attribute information A1(1) to A1(N) of N-number of vertexes which constitute a three-dimensional mesh. In addition, in the example, M-number of pieces of attribute information A2(1) to A2(M) are included. An item of attribute information need not correspond one-to-one to a vertex and need not correspond one-to-one to a face. In addition, attribute information need not exist.

Connection information is indicated by a combination of indexes of vertexes. n [1, 3, 4] indicates a face of a triangle constituted of three vertexes n=1, n=3, and n=4. In addition, m[2, 4, 6] indicates that pieces of attribute information m=2, m=4, and m=6 respectively correspond to the three vertexes.

In addition, a substantive content of the attribute information may be described in a separate file. Furthermore, a pointer with respect to the content may be associated with a vertex, a face, or the like. For example, attribute information indicating an image with respect to a face may be stored in a two-dimensional attribute map file. In addition, a file name of the attribute map and a two-dimensional coordinate value in the attribute map may be described in pieces of attribute information A2(1) to A2(M). Methods of designating attribute information with respect to a face are not limited to these methods and any kind of method may be used.

17 FIG. is a conceptual diagram illustrating a type of three-dimensional data according to the present embodiment. Point cloud data and mesh data may either indicate a static object or a dynamic object. A static object is an object that does not temporally change, and a dynamic object is an object that temporally changes. A static object may correspond to three-dimensional data with respect to an arbitrary time point.

For example, point cloud data with respect to an arbitrary time point may be expressed as a PCC frame. In addition, mesh data with respect to an arbitrary time point may be expressed as a mesh frame. Furthermore, a PCC frame and a mesh frame may be simply expressed as a frame.

In addition, an area of an object may be limited to a certain range in a similar manner to ordinary video data or need not be limited in a similar manner to map data. Furthermore, a density of points or faces may be set in various ways. Sparse point cloud data or sparse mesh data may be used, or dense point cloud data or dense mesh data may be used.

Next, encoding and decoding of a point cloud or a three-dimensional mesh will be described. A device, processing, or a syntax for encoding and decoding vertex information of a three-dimensional mesh according to the present disclosure may be applied to the encoding and decoding of a point cloud. A device, processing, or a syntax for encoding and decoding a point cloud according to the present disclosure may be applied to the encoding and decoding of vertex information of a three-dimensional mesh.

In addition, a device, processing, or a syntax for encoding and decoding attribute information of a point cloud according to the present disclosure may be applied to the encoding and decoding of connection information or attribute information of a three-dimensional mesh. Furthermore, a device, processing, or a syntax for encoding and decoding connection information or attribute information of a three-dimensional mesh according to the present disclosure may be applied to the encoding and decoding of attribute information of a point cloud.

Furthermore, at least a part of processing may be commonalized between the encoding and decoding of point cloud data and the encoding and decoding of mesh data. Accordingly, sizes of circuits and software programs can be suppressed.

18 FIG. 6 FIG. 113 113 121 122 123 124 121 122 124 101 103 105 is a block diagram illustrating a configuration example of three-dimensional data encoderaccording to the present embodiment. In this example, three-dimensional data encoderincludes vertex information encoder, attribute information encoder, metadata encoder, and multiplexer. Vertex information encoder, attribute information encoder, and multiplexermay correspond to vertex information encoder, attribute information encoder, postprocessor, and the like illustrated in.

113 In addition, in this example, three-dimensional data encoderencodes three-dimensional data according to a geometry-based encoding system. Encoding according to the geometry-based encoding system takes a three-dimensional structure into consideration. Furthermore, in encoding according to the geometry-based encoding system, attribute information is encoded using configuration information obtained during encoding of vertex information.

121 122 123 Specifically, first, vertex information, attribute information, and metadata included in three-dimensional data generated from sensor data are respectively input to vertex information encoder, attribute information encoder, and metadata encoder. In this case, connection information included in three-dimensional data may be handled in a similar manner to attribute information. In addition, in the case of point cloud data, position information may be handled as vertex information.

121 124 121 124 121 122 Vertex information encoderencodes vertex information into compressed vertex information and outputs the compressed vertex information to multiplexeras encoded data. In addition, vertex information encodergenerates metadata of the compressed vertex information and outputs the metadata to multiplexer. Furthermore, vertex information encodergenerates configuration information and outputs the configuration information to attribute information encoder.

122 121 124 122 124 Attribute information encoderencodes attribute information into compressed attribute information using the configuration information generated by vertex information encoderand outputs the compressed attribute information to multiplexeras encoded data. In addition, attribute information encodergenerates metadata of the compressed attribute information and outputs the metadata to multiplexer.

123 124 123 Metadata encoderencodes compressible metadata into compressed metadata and outputs the compressed metadata to multiplexeras encoded data. The metadata encoded by metadata encodermay be used to encode vertex information and to encode attribute information.

124 124 Multiplexermultiplexes the compressed vertex information, the metadata of the compressed vertex information, the compressed attribute information, the metadata of the compressed attribute information, and the compressed metadata into a bitstream. In addition, multiplexerinputs the bitstream into a system layer.

19 FIG. 8 FIG. 213 213 221 222 223 224 221 222 224 201 203 204 is a block diagram illustrating a configuration example of three-dimensional data decoderaccording to the present embodiment. In this example, three-dimensional data decoderincludes vertex information decoder, attribute information decoder, metadata decoder, and demultiplexer. Vertex information decoder, attribute information decoder, and demultiplexermay correspond to vertex information decoder, attribute information decoder, preprocessor, and the like illustrated in.

213 In addition, in this example, three-dimensional data decoderdecodes three-dimensional data according to a geometry-based encoding system. Decoding according to the geometry-based encoding system takes a three-dimensional structure into consideration. Furthermore, in decoding according to the geometry-based encoding system, attribute information is decoded using configuration information obtained during decoding of vertex information.

224 224 221 222 223 Specifically, first, a bitstream is input from a system layer into demultiplexer. Demultiplexerseparates compressed vertex information, metadata of the compressed vertex information, compressed attribute information, metadata of the compressed attribute information, and compressed metadata from the bitstream. The compressed vertex information and the metadata of the compressed vertex information are input to vertex information decoder. The compressed attribute information and the metadata of the compressed attribute information are input to attribute information decoder. The metadata is input to metadata decoder.

221 221 222 222 221 223 223 Vertex information decoderdecodes vertex information from the compressed vertex information using the metadata of the compressed vertex information. In addition, vertex information decodergenerates configuration information and outputs the configuration information to attribute information decoder. Attribute information decoderdecodes attribute information from the compressed attribute information using the configuration information generated by vertex information decoderand the metadata of the compressed attribute information. Metadata decoderdecodes metadata from the compressed metadata. The metadata decoded by metadata decodermay be used to decode vertex information and to decode attribute information.

213 Subsequently, the vertex information, the attribute information, and the metadata are output from three-dimensional data decoderas three-dimensional data. For example, the metadata is metadata of vertex information and attribute information and can be used in an application program.

20 FIG. 6 FIG. 113 113 131 132 133 134 123 124 131 132 134 101 103 is a block diagram illustrating another configuration example of three-dimensional data encoderaccording to the present embodiment. In this example, three-dimensional data encoderincludes vertex image generator, attribute image generator, metadata generator, video encoder, metadata encoder, and multiplexer. Vertex image generator, attribute image generator, and video encodermay correspond to vertex information encoder, attribute information encoder, and the like illustrated in.

113 In addition, in this example, three-dimensional data encoderencodes three-dimensional data according to a video-based encoding system. In encoding according to the video-based encoding system, a plurality of two-dimensional images are generated from three-dimensional data and the plurality of two-dimensional images are encoded according to a video encoding system. In this case, the video encoding system may be HEVC (high efficiency video coding), VVC (versatile video coding), or the like.

133 131 132 123 Specifically, first, vertex information and attribute information included in three-dimensional data generated from sensor data are input to metadata generator. In addition, the vertex information and the attribute information are respectively input to vertex image generatorand attribute image generator. Furthermore, the metadata included in the three-dimensional data is input to metadata encoder. In this case, connection information included in three-dimensional data may be handled in a similar manner to attribute information. In addition, in the case of point cloud data, position information may be handled as vertex information.

133 133 131 132 123 Metadata generatorgenerates map information of a plurality of two-dimensional images from the vertex information and the attribute information. In addition, metadata generatorinputs the map information into vertex image generator, attribute image generator, and metadata encoder.

131 134 132 134 Vertex image generatorgenerates a vertex image based on the vertex information and the map information and inputs the vertex image into video encoder. Attribute image generatorgenerates an attribute image based on the attribute information and the map information and inputs the attribute image into video encoder.

134 124 134 124 Video encoderrespectively encodes the vertex image and the attribute image into compressed vertex information and compressed attribute information according to the video encoding system and outputs the compressed vertex information and the compressed attribute information to multiplexeras encoded data. In addition, video encodergenerates metadata of the compressed vertex information and metadata of the compressed attribute information and outputs the pieces of metadata to multiplexer.

123 124 123 Metadata encoderencodes compressible metadata into compressed metadata and outputs the compressed metadata to multiplexeras encoded data. Compressible metadata includes map information. In addition, the metadata encoded by metadata encodermay be used to encode vertex information and to encode attribute information.

124 124 Multiplexermultiplexes the compressed vertex information, the metadata of the compressed vertex information, the compressed attribute information, the metadata of the compressed attribute information, and the compressed metadata into a bitstream. In addition, multiplexerinputs the bitstream into a system layer.

21 FIG. 8 FIG. 213 213 231 232 234 223 224 231 232 234 201 203 is a block diagram illustrating another configuration example of three-dimensional data decoderaccording to the present embodiment. In this example, three-dimensional data decoderincludes vertex information generator, attribute information generator, video decoder, metadata decoder, and demultiplexer. Vertex information generator, attribute information generator, and video decodermay correspond to vertex information decoder, attribute information decoder, and the like illustrated in.

213 In addition, in this example, three-dimensional data decoderdecodes three-dimensional data according to a video-based encoding system. In decoding according to the video-based encoding system, a plurality of two-dimensional images are decoded according to a video encoding system and three-dimensional data is generated from the plurality of two-dimensional images. In this case, the video encoding system may be HEVC (high efficiency video coding), VVC (versatile video coding), or the like.

224 224 234 223 Specifically, first, a bitstream is input from a system layer into demultiplexer. Demultiplexerseparates compressed vertex information, metadata of the compressed vertex information, compressed attribute information, metadata of the compressed attribute information, and compressed metadata from the bitstream. The compressed vertex information, the metadata of the compressed vertex information, the compressed attribute information, and the metadata of the compressed attribute information are input to video decoder. The compressed metadata is input to metadata decoder.

234 234 234 231 234 234 234 232 Video decoderdecodes a vertex image according to the video encoding system. In doing so, video decoderdecodes the vertex image from the compressed vertex information using the metadata of the compressed vertex information. In addition, video decoderinputs the vertex image into vertex information generator. Furthermore, video decoderdecodes an attribute image according to the video encoding system. In doing so, video decoderdecodes the attribute image from the compressed attribute information using the metadata of the compressed attribute information. In addition, video decoderinputs the attribute image into attribute information generator.

223 223 223 Metadata decoderdecodes metadata from the compressed metadata. The metadata decoded by metadata decoderincludes map information to be used to generate vertex information and to generate attribute information. In addition, the metadata decoded by metadata decodermay be used to decode the vertex image and to decode the attribute image.

231 223 232 223 Vertex information generatorreproduces vertex information from the vertex image according to the map information included in the metadata decoded by metadata decoder. Attribute information generatorreproduces attribute information from the attribute image according to the map information included in the metadata decoded by metadata decoder.

213 Subsequently, the vertex information, the attribute information, and the metadata are output from three-dimensional data decoderas three-dimensional data. For example, the metadata is metadata of vertex information and attribute information and can be used in an application program.

22 FIG. 22 FIG. 113 148 113 141 142 141 143 142 144 145 is a conceptual diagram illustrating a specific example of encoding processing according to the present embodiment.illustrates three-dimensional data encoderand description encoder. In this example, three-dimensional data encoderincludes two-dimensional data encoderand mesh data encoder. Two-dimensional data encoderincludes texture encoder. Mesh data encoderincludes vertex information encoderand connection information encoder.

144 145 143 101 102 103 6 FIG. Vertex information encoder, connection information encoder, and texture encodermay correspond to vertex information encoder, connection information encoder, attribute information encoder, and the like illustrated in.

141 143 For example, two-dimensional data encoderoperates as texture encoderand generates a texture file by encoding a texture corresponding to attribute information as two-dimensional data according to an image encoding system or a video encoding system.

142 144 145 142 In addition, mesh data encoderoperates as vertex information encoderand connection information encoderand generates a mesh file by encoding vertex information and connection information. Mesh data encodermay further encode mapping information with respect to a texture. The encoded mapping information may be included in a mesh file.

148 148 148 114 12 FIG. In addition, description encodergenerates a description file by encoding a description corresponding to metadata such as text data. Description encodermay encode a description in the system layer. For example, description encodermay be included in system multiplexerillustrated in.

Due to the operation described above, a bitstream including a texture file, a mesh file, and a description file is generated. The files may be multiplexed in the bitstream in a file format such as glTF (graphics language transmission format) or USD (universal scene description).

113 142 Note that three-dimensional data encodermay include two mesh data encoders as mesh data encoder. For example, one mesh data encoder encodes vertex information and connection information of a static three-dimensional mesh and the other mesh data encoder encodes vertex information and connection information of a dynamic three-dimensional mesh.

In addition, two mesh files may be included in the bitstream so as to correspond to the three-dimensional meshes. For example, one mesh file corresponds to the static three-dimensional mesh and the other mesh file corresponds to the dynamic three-dimensional mesh.

Furthermore, the static three-dimensional mesh may be an intra-frame three-dimensional mesh which is encoded using intra-prediction and the dynamic three-dimensional mesh may be an inter-frame three-dimensional mesh which is encoded using inter-prediction. In addition, as information of the dynamic three-dimensional mesh, difference information between vertex information or connection information of the intra-frame three-dimensional mesh and vertex information or connection information of the inter-frame three-dimensional mesh may be used.

23 FIG. 23 FIG. 213 248 247 213 241 242 246 241 243 242 244 245 is a conceptual diagram illustrating a specific example of decoding processing according to the present embodiment.illustrates three-dimensional data decoder, description decoder, and presenter. In this example, three-dimensional data decoderincludes two-dimensional data decoder, mesh data decoder, and mesh reconstructor. Two-dimensional data decoderincludes texture decoder. Mesh data decoderincludes vertex information decoderand connection information decoder.

244 245 243 246 201 202 203 205 247 215 8 FIG. 12 FIG. Vertex information decoder, connection information decoder, texture decoder, and mesh reconstructormay correspond to vertex information decoder, connection information decoder, attribute information decoder, postprocessor, and the like illustrated in. Presentermay correspond to presenterand the like illustrated in.

241 243 For example, two-dimensional data decoderoperates as texture decoderand decodes a texture corresponding to attribute information from a texture file as two-dimensional data according to an image encoding system or a video encoding system.

242 244 245 242 In addition, mesh data decoderoperates as vertex information decoderand connection information decoderand decodes vertex information and connection information from a mesh file. Mesh data decodermay further decode mapping information with respect to a texture from the mesh file.

248 248 248 214 12 FIG. Furthermore, description decoderdecodes a description corresponding to metadata such as text data from a description file. Description decodermay decode a description in the system layer. For example, description decodermay be included in system demultiplexerillustrated in.

246 247 Mesh reconstructorreconstructs a three-dimensional mesh from vertex information, connection information, and a texture according to a description. Presenterrenders and outputs the three-dimensional mesh according to the description.

Due to the operation described above, a three-dimensional mesh is reconstructed and output from a bitstream including a texture file, a mesh file, and a description file.

213 242 Note that three-dimensional data decodermay include two mesh data decoders as mesh data decoder. For example, one mesh data decoder decodes vertex information and connection information of a static three-dimensional mesh and the other mesh data decoder decodes vertex information and connection information of a dynamic three-dimensional mesh.

In addition, two mesh files may be included in the bitstream so as to correspond to the three-dimensional meshes. For example, one mesh file corresponds to the static three-dimensional mesh and the other mesh file corresponds to the dynamic three-dimensional mesh.

Furthermore, the static three-dimensional mesh may be an intra-frame three-dimensional mesh which is encoded using intra-prediction and the dynamic three-dimensional mesh may be an inter-frame three-dimensional mesh which is encoded using inter-prediction. In addition, as information of the dynamic three-dimensional mesh, difference information between vertex information or connection information of the intra-frame three-dimensional mesh and vertex information or connection information of the inter-frame three-dimensional mesh may be used.

An encoding system of a dynamic three-dimensional mesh may be called DMC (dynamic mesh coding). In addition, a video-based encoding system of a dynamic three-dimensional mesh may be called VDMC (video-based dynamic mesh coding).

An encoding system of a point cloud may be called PCC (point cloud compression). A video-based encoding system of a point cloud may be called V-PCC (video-based point cloud compression). In addition, a geometry-based encoding system of a point cloud may be called G-PCC (geometry-based point cloud compression).

24 FIG. 5 FIG. 24 FIG. 100 100 151 152 100 151 152 is a block diagram illustrating an implementation example of encoding deviceaccording to the present embodiment. Encoding deviceincludes circuitand memory. For example, a plurality of constituent elements of encoding deviceillustrated inand the like are implemented by circuitand memoryillustrated in.

151 152 151 151 151 Circuitis a circuit which performs information processing and which is capable of accessing memory. For example, circuitis a dedicated or general-purpose electric circuit which encodes a three-dimensional mesh. Circuitmay be a processor such as a CPU. Alternatively, circuitmay be a set of a plurality of electric circuits.

152 151 152 151 152 151 152 152 152 Memoryis a dedicated or general-purpose memory that stores information used by circuitto encode a three-dimensional mesh. Memorymay be an electric circuit and may be connected to circuit. In addition, memorymay be included in circuit. Alternatively, memorymay be a set of a plurality of electric circuits. Furthermore, memorymay be a magnetic disk, an optical disk, or the like or may be expressed as a storage, a recording medium, or the like. In addition, memorymay be a non-volatile memory or a volatile memory.

152 152 151 For example, memorymay store a three-dimensional mesh or a bitstream. In addition, memorymay store a program used by circuitto encode a three-dimensional mesh.

100 100 5 FIG. 5 FIG. Note that in encoding device, all of the plurality of constituent elements illustrated inand the like need not be implemented and all of the plurality of processing steps described herein need not be performed. A part of the plurality of constituent elements illustrated inand the like may be included in another device and a part of the plurality of processing steps described herein may be executed by another device. In addition, a plurality of constituent elements according to the present disclosure may be optionally combined and implemented or a plurality of processing steps according to the present disclosure may be optionally combined and executed in encoding device.

25 FIG. 7 FIG. 25 FIG. 200 200 251 252 200 251 252 is a block diagram illustrating an implementation example of decoding deviceaccording to the present embodiment. Decoding deviceincludes circuitand memory. For example, a plurality of constituent elements of decoding deviceillustrated inand the like are implemented by circuitand memoryillustrated in.

251 252 251 251 251 Circuitis a circuit which performs information processing and which is capable of accessing memory. For example, circuitis a dedicated or general-purpose electric circuit which decodes a three-dimensional mesh. Circuitmay be a processor such as a CPU. Alternatively, circuitmay be a set of a plurality of electric circuits.

252 251 252 251 252 251 252 252 252 Memoryis a dedicated or general-purpose memory that stores information used by circuitto decode a three-dimensional mesh. Memorymay be an electric circuit and may be connected to circuit. In addition, memorymay be included in circuit. Alternatively, memorymay be a set of a plurality of electric circuits. Furthermore, memorymay be a magnetic disk, an optical disk, or the like or may be expressed as a storage, a recording medium, or the like. In addition, memorymay be a non-volatile memory or a volatile memory.

252 252 251 For example, memorymay store a three-dimensional mesh or a bitstream. In addition, memorymay store a program used by circuitto decode a three-dimensional mesh.

200 200 7 FIG. 7 FIG. Note that in decoding device, all of the plurality of constituent elements illustrated inand the like need not be implemented and all of the plurality of processing steps described herein need not be performed. A part of the plurality of constituent elements illustrated inand the like may be included in another device and a part of the plurality of processing steps described herein may be executed by another device. In addition, a plurality of constituent elements according to the present disclosure may be optionally combined and implemented or a plurality of processing steps according to the present disclosure may be optionally combined and executed in decoding device.

100 200 An encoding method and a decoding method including steps performed by each constituent element of encoding deviceand decoding deviceaccording to the present disclosure may be executed by any device or system. For example, a part of or all of the encoding method and the decoding method may be executed by a computer including a processor, a memory, an input/output circuit, and the like. In doing so, the encoding method and the decoding method may be executed by having the computer execute a program that enables the computer to execute the encoding method and the decoding method.

In addition, a program or a bitstream may be recorded on a non-transitory computer-readable recording medium such as a CD-ROM.

200 200 An example of a program may be a bitstream. For example, a bitstream including an encoded three-dimensional mesh includes a syntax element that enables decoding deviceto decode the three-dimensional mesh. In addition, the bitstream causes decoding deviceto decode the three-dimensional mesh according to the syntax element included in the bitstream. Therefore, a bitstream can perform a similar role to a program.

The bitstream described above may be an encoded bitstream including an encoded three-dimensional mesh or a multiplexed bitstream including an encoded three-dimensional mesh and other information.

100 200 In addition, each constituent element of encoding deviceand decoding devicemay be constituted of dedicated hardware, general-purpose hardware which executes the program or the like described above, or a combination thereof. Furthermore, the general-purpose hardware may be constituted of a memory on which a program is recorded, a general-purpose processor which reads the program from the memory and executes the program, and the like. In this case, the memory may be a semiconductor memory, a hard disk, or the like and the general-purpose processor may be a CPU or the like.

Furthermore, the dedicated hardware may be constituted of a memory, a dedicated processor, and the like. For example, the dedicated processor may execute the encoding method and the decoding method by referring to a memory for recording data.

100 200 100 200 In addition, as described above, the respective constituent elements of encoding deviceand decoding devicemay be electric circuits. The electric circuits may constitute one electric circuit as a whole or may be respectively different electric circuits. Furthermore, the electric circuits may correspond to dedicated hardware or to general-purpose hardware which executes the program or the like described above. Moreover, encoding deviceand decoding devicemay be implemented as integrated circuits.

100 200 In addition, encoding devicemay be a transmitting device which transmits a three-dimensional mesh. Decoding devicemay be a receiving device which receives a three-dimensional mesh.

A generic three-dimensional model represents an object digitally such that a user can explore the three-dimensional model by using zooming, panning, and/or rotation in all three dimensions while rendering it temporally. One way to construct such representation is to construct a three-dimensional mesh. The three-dimensional mesh uses faces that are formed by connecting vertices via edges to represent a surface of the object. The majority of three-dimensional meshes uses triangular faces. For example, one of a plurality of faces forming a three-dimensional mesh contains three vertices. Additionally, the three-dimensional mesh may be parametrized to generate a two-dimensional UV map. This is used to project attributes represented in the two-dimensional format onto the surface of the three-dimensional mesh. For example, a renderer can project texture information stored in a two-dimensional image onto a three-dimensional mesh using the three-dimensional mesh's associated UV map. Storing all this information in the uncompressed form needs an extremely large storage space. Thus, transmission of such information requires an extremely high bandwidth. The triangles forming the three-dimensional mesh often have repetitive patterns and similar attributes, especially in the temporal and spatial neighborhood. These repetitions can be used to formulate an efficient encoding method and decoding method for storage and transmission. One such encoding method and decoding method is Video-based Dynamic Mesh Coding (V-DMC).

26 FIG. is a block diagram illustrating a configuration example of an encoding and decoding system according to the present embodiment.

100 100 100 Encoding devicetakes in an input mesh (a three-dimensional mesh frame inputted to encoding device) in the form of three-dimensional coordinates of vertices (vertex coordinates), connection information, and associated attributes. Encoding deviceis responsible for encoding all the relevant information into a bitstream.

300 100 200 300 300 300 200 300 Networktransmits the bitstream generated by encoding deviceto decoding device. Networkmay be the Internet, the Wide Area Network (WAN), the Local Area Network (LAN), or any combination of these networks. Networkis not necessarily limited to a bi-directional communication network, and may be a uni-directional communication network which transmits broadcast waves of digital terrestrial broadcasting, satellite broadcasting, or the like. Alternatively, networkmay be replaced by a recording medium such as a Digital Versatile Disc (DVD) and a Blu-Ray Disc (BD), etc. on which a bitstream is recorded. The bitstream is transmitted to decoding devicethrough network.

200 Decoding devicedecodes the bitstream to generate a three-dimensional mesh frame (an output mesh) using decoded three-dimensional coordinates of vertices, decoded connectivity, and decoded associated attributes.

27 FIG. 100 is a block diagram illustrating another configuration example of encoding deviceaccording to the present embodiment.

27 FIG. 100 1103 1106 As illustrated in, encoding deviceincludes preprocessorand compressor.

100 1101 1102 1103 Encoding devicereads input meshand attribute imageand outputs them to preprocessor.

1103 1104 1105 1101 1102 1104 1105 1102 1106 Preprocessorextracts base meshand displacement databy processing input mesh. An example of attribute imageis a texture (texture data) represented by an image (a texture image). Along with extracted base meshand displacement data, attribute imageis outputted to compressor.

1106 1104 1105 1102 1107 1108 1107 1106 200 Compressorcompresses base mesh, displacement data, and attribute imageto generate bitstream. By additionally including metadatainto bitstream, compressorcan transmit supplementary information to decoding device.

28 FIG. 200 is a block diagram illustrating another configuration example of decoding deviceaccording to the present embodiment.

28 FIG. 200 2102 2106 As illustrated in, decoding deviceincludes decompressorand reconstructor.

200 2101 2102 Decoding devicereads bitstreamand outputs it to decompressor.

2102 2103 2104 2108 2101 2106 2108 2104 Decompressordecompresses base mesh, displacement data, and attribute imagefrom bitstreamand outputs them to reconstructor. An example of attribute imageis texture data represented by an image. An example of displacement datais a displacement vector.

2106 2107 2103 2104 2108 2106 2107 2105 Reconstructorgenerates output meshby processing base meshaccording to displacement dataand attribute image. Reconstructormay generate output meshby additionally using information from metadata.

29 FIG. 100 is a block diagram illustrating yet another configuration example of encoding deviceaccording to the present embodiment.

100 511 512 513 514 515 516 In the present example, encoding deviceincludes volumetric capturer, projector, base mesh encoder, displacement encoder, attribute encoder, and optionally one or more other type encoders.

511 512 Volumetric capturercaptures content and outputs the captured content to projector.

512 513 514 515 516 Projectorprojects the content onto an input mesh (a three-dimensional mesh frame) that includes, for example, geometry coordinates (vertex coordinates indicating the positions of vertices), texture coordinates, and connectivity (connection information). The data are outputted to base mesh encoder, displacement encoder, attribute encoder, and optionally one or more other type encoders. Each encoder compresses the data into a bitstream.

30 FIG. 200 is a block diagram illustrating yet another configuration example of decoding deviceaccording to the present embodiment.

200 613 614 615 616 617 In the present example, decoding deviceincludes base mesh decoder, displacement decoder, attribute decoder, one or more other type decoders, and three-dimensional reconstructor.

613 614 615 616 617 A bitstream is sent to base mesh decoder, displacement decoder, attribute decoder, and optionally one or more other type decoders. By decoding the bitstream, these decoders generate data (decoded data) that includes, for example, geometry coordinates, texture coordinates, and connectivity. The decoded data is then sent to three-dimensional reconstructorto reconstruct an output mesh (a three-dimensional mesh frame).

100 Hereinafter, an encoding process performed by encoding devicewill be described in detail.

31 FIG. 32 FIG. 31 FIG. 32 FIG. 100 100 is a flowchart illustrating the process performed by encoding device.is an explanatory diagram schematically illustrating the encoding of a mesh frame. With reference toand, the process performed by encoding devicewill be described.

101 100 100 1301 32 FIG. In step S, encoding devicereads a three-dimensional mesh frame, which is an input mesh frame, and its attributes. The input mesh frame is a mesh frame inputted into encoding device. An example of the three-dimensional mesh frame, which is the input mesh frame, is illustrated as mesh frame(see).

102 100 101 1301 1302 32 FIG. In step S, encoding deviceperforms the decimating process on the input mesh frame that is read in step Sto generate a base mesh frame, which has a smaller number of vertices than the input mesh frame. The base mesh frame generated by decimating mesh frameis illustrated as base mesh frame(see).

103 100 200 102 1301 1302 1303 1303 1303 32 FIG. In step S, encoding devicecalculates displacement information to be used by decoding deviceto reconstruct the mesh frame. The displacement information is equivalent to displacement vectors from the vertices of the base mesh frame generated in step Sto the vertices of the input mesh frame. Methods of calculating the displacement information include a method in which the sets of coordinates of the vertices of the base mesh frame are subtracted from the coordinates of the vertices of the input mesh frame. The displacement information calculated from mesh frameand base mesh frameis illustrated as displacement information(see). Displacement informationis in a vector format. In other words, displacement informationis represented as displacement vectors.

104 100 102 103 1304 32 FIG. In step S, encoding deviceencodes the base mesh frame generated in step S, the displacement information generated in step S, and the attributes of the input mesh frame into a bitstream (equivalent to a compressed bitstream). An example of the bitstream is illustrated as bitstream(see).

32 FIG. 1304 As illustrated in, for example, bitstreamincludes: a bitstream including the base mesh frame (a base mesh sub-bitstream); a bitstream including displacement information (a displacement information sub-bitstream); a bitstream including texture data (a texture sub-bitstream); and metadata.

The base mesh sub-bitstream includes information indicating, for example, vertex coordinates and connectivity (connection information) of vertices A, C, E, and F.

The displacement information sub-bitstream includes displacement information indicating displacement coordinates for displacing the vertices based on the vertex coordinates obtained from the subdivided base mesh frame.

200 The metadata is data that allows decoding deviceto reconstruct a three-dimensional mesh frame by using the base mesh frame, the displacement information, and the texture data.

100 1301 1302 1301 First, encoding devicedecimates mesh frameto acquire base mesh framecontaining fewer vertices than mesh frame. After decimation, there is a possibility that the vertices are not in the original positions and that the vertex connectivity changes.

100 1302 Next, encoding deviceperforms texture parametrization on base mesh frameto generate texture coordinates (two-dimensional texture coordinates) also known as a UV map.

100 1302 1302 Subsequently, encoding devicesubdivides base mesh frameby adding new vertices between the existing connected vertices of base mesh frame.

100 1303 1301 1301 1303 1301 1304 Next, encoding devicecalculates displacement informationusing the subdivided mesh frame and mesh frameto move (displace) the vertices generated by the subdivision. In an example, the vertices generated by the subdivision are moved to positions similar to mesh frame. Displacement informationis transformed by wavelet transformation into wavelet coefficients and encoded using a video codec by mapping the coefficients onto planes of a video frame. The texture data in mesh frameand the metadata are also encoded and included into bitstream.

200 Hereinafter, a decoding process performed by decoding devicewill be described in detail.

33 FIG. 34 FIG. 33 FIG. 34 FIG. 200 200 is a flowchart illustrating the process performed by decoding device.is an explanatory diagram schematically illustrating the decoding of a mesh frame. With reference toand, the process performed by decoding devicewill be described.

201 200 2301 34 FIG. In step S, decoding devicedecodes a base mesh frame and attributes from a bitstream (equivalent to a compressed bitstream). An example of the decoded base mesh frame (equivalent to a decoded base mesh frame) is illustrated as decoded base mesh frame(see).

202 200 201 2302 34 FIG. In step S, decoding deviceperforms the subdivision process on the base mesh frame decoded in step Sto generate subdivided vertices. An example of the mesh frame (base mesh frame) including the subdivided vertices is illustrated as mesh frame(see).

203 200 2303 2303 2303 34 FIG. In step S, decoding devicedecodes displacement information from the bitstream (equivalent to the compressed bitstream). An example of the decoded displacement information is illustrated as displacement information(see). Displacement informationis in a vector format. In other words, displacement informationis represented as displacement vectors.

204 200 2304 34 FIG. In step S, using the displacement information, decoding devicemoves the vertices of the base mesh frame including the subdivided vertices to new positions to reconstruct the shape of the mesh frame and further applies attribute information to restore the mesh frame. An example of the attributes is a texture. An example of the reconstructed mesh frame is illustrated as mesh frame(see).

34 FIG. 200 2301 2301 2301 200 2301 2301 200 2302 As illustrated in, first, decoding devicedecodes base mesh frame. Base mesh framedecoded may include texture coordinates for the vertices of base mesh frame. Alternatively, high-level syntax parameters may be used by decoding deviceto apply parametrization of texture (texture parametrization) to base mesh frame. By subdividing base mesh framemultiple times, decoding devicemay generate (create) mesh frameincluding vertices subdivided through addition of new vertices between the already connected vertices.

200 2303 2303 2302 2304 After this processing, all the vertices and connectivity are obtained. The wavelet coefficients are decoded by decoding device, and inverse wavelet transformation is applied to reconstruct displacement information. Displacement informationis used to move the vertices of mesh framesubdivided. The texture is mapped on the faces created by the vertices and their connectivity. Accordingly, a fully decoded mesh (reconstructed mesh frame) is obtained.

100 200 200 The texture coordinates of the base mesh frame may be generated by encoding deviceand signaled in the base mesh sub-bitstream to decoding device. Alternatively, a set of high-level syntax parameters may be included in the compressed bitstream which is used by decoding deviceto derive a UV map of the base mesh frame.

35 FIG. 100 100 701 702 703 704 705 706 707 708 709 710 711 712 is a block diagram illustrating yet another configuration example of encoding deviceaccording to the embodiment. In the present example, encoding deviceincludes decimator, base mesh encoder, base mesh decoder, texture parametrizer, subdivider, displacement vector calculator, displacement information encoder, displacement information decoder, mesh reconstructor, texture converter, video encoder, and multiplexer.

100 701 706 710 710 Encoding devicereceives inputs of an original three-dimensional mesh frame and an original texture map. The original three-dimensional mesh frame is inputted to decimator, displacement vector calculator, and texture converter. The original texture map is inputted to texture converter.

701 702 Decimatordecimates the original three-dimensional mesh frame to generate a base mesh frame, and outputs the generated base mesh frame to base mesh encoder.

702 702 712 703 Base mesh encoderencodes the base mesh frame. For example, base mesh encoderoutputs a base mesh bitstream (for example, the base mesh sub-bitstream described above) including the encoded base mesh frame to multiplexerand base mesh decoder.

703 704 Base mesh decoderdecodes the base mesh frame from the base mesh bitstream and outputs the decoded base mesh frame to texture parametrizer.

704 705 704 Texture parametrizercalculates texture coordinates based on the decoded base mesh frame, and outputs the calculated texture coordinates and the decoded base mesh frame to subdivider. Specifically, texture parametrizerdevelops the restored base mesh frame on a two-dimensional plane, and calculates, as texture coordinates (UV coordinates), two-dimensional coordinates corresponding to the vertices of each face (for example, each triangle included in the three-dimensional mesh frame) of the base mesh frame.

705 706 709 705 709 705 Subdividersubdivides the decoded base mesh frame, and outputs the subdivided, decoded base mesh frame to displacement vector calculatorand mesh reconstructor. Subdivideralso outputs the calculated texture coordinates to mesh reconstructor. Specifically, subdividerfractionalizes the faces of the restored base mesh frame by subdivision.

706 707 706 Displacement vector calculatorcalculates displacement vectors based on the original three-dimensional mesh frame and the subdivided, decoded base mesh frame, and outputs the calculated displacement vectors as displacement information to displacement information encoder. Specifically, displacement vector calculatorderives, according to the original three-dimensional mesh frame received, the displacement vectors of the vertices of the subdivided, restored base mesh frame.

707 707 712 708 Displacement information encoderencodes displacement information. For example, displacement information encoderoutputs a displacement information bitstream (for example, the displacement information sub-bitstream described above) including the encoded displacement information to multiplexerand displacement information decoder.

708 709 Displacement information decoderdecodes the displacement information from the displacement information bitstream, and outputs the decoded displacement information to mesh reconstructor.

709 709 709 710 Mesh reconstructordecodes (reconstructs) the mesh frame, based on the subdivided, decoded base mesh frame and the decoded displacement information. Specifically, mesh reconstructordecodes the mesh frame by displacing each vertex of the subdivided, decoded base mesh frame, based on the displacement information. Mesh reconstructoroutputs the mesh frame decoded in the above-described manner and the calculated texture coordinates to texture converter.

710 711 710 Texture converterconverts the original texture map, based on the decoded mesh frame, the calculated texture coordinates, and the original three-dimensional mesh frame, and outputs the converted texture map to video encoder. Specifically, texture converterconverts the received original texture map according to the two-dimensional coordinates corresponding to the vertices of each face of the restored base mesh frame.

711 711 712 Video encoderencodes the converted texture map. For example, video encoderoutputs an attribute information bitstream (for example, the texture sub-bitstream described above) including, as an attribute (attribute information), the encoded, converted texture map to multiplexer.

712 Multiplexergenerates and outputs a compressed bitstream including: the base mesh bitstream; the displacement information bitstream; and the attribute information bitstream.

36 FIG. 200 200 801 802 803 804 805 806 807 is a block diagram illustrating yet another configuration example of decoding deviceaccording to the embodiment. In the present example, decoding deviceincludes demultiplexer, base mesh decoder, texture parametrizer, subdivider, displacement information decoder, mesh reconstructor, and video decoder.

200 801 Decoding devicereceives an input of a compressed bitstream. The compressed bitstream is inputted to demultiplexer.

801 801 802 805 807 Demultiplexerseparates the compressed bitstream into a base mesh bitstream, a displacement information bitstream, and an attribute information bitstream. Demultiplexeroutputs the base mesh bitstream to base mesh decoder, outputs the displacement information bitstream to displacement information decoder, and outputs the attribute information bitstream to video decoder.

802 803 Base mesh decoderdecodes the base mesh frame from the base mesh bitstream and outputs the decoded base mesh frame to texture parametrizer.

803 804 Texture parametrizercalculates texture coordinates, based on the decoded base mesh frame, and outputs the calculated texture coordinates and the decoded base mesh frame to subdivider.

804 806 Subdividersubdivides the decoded base mesh frame, and outputs the subdivided, decoded base mesh frame and the calculated texture coordinates to mesh reconstructor.

805 806 Displacement information decoderdecodes the displacement information from the displacement information bitstream, and outputs the decoded displacement information to mesh reconstructor.

806 806 806 Mesh reconstructordecodes (reconstructs) the mesh frame, based on the decoded displacement information and the subdivided, decoded base mesh frame. Specifically, mesh reconstructordecodes the mesh frame by displacing each vertex of the subdivided, decoded base mesh frame, based on the displacement information. Mesh reconstructoroutputs the mesh frame decoded in the above-described manner and the calculated texture coordinates.

807 Video decoderdecodes the texture map from the attribute information bitstream, and outputs the decoded texture map.

A textured mesh frame is reconstructed based on the decoded mesh frame, the calculated texture coordinates, and the decoded texture map that have been outputted in the above-described manner.

Note that an intra coding process or an inter coding process may be performed on the base mesh frame, based on a parameter in the bitstream. For example, an edge-breaker algorithm may be used for decoding the base mesh frame.

200 The displacement information may be included in a bitstream in an image format having two chroma information items and one luma information item, and may be decoded using a video frame decompression method. The displacement information may be decoded using arithmetic decoding. Decoding device, for example, may extract the wavelet coefficients related to each vertex from decompressed data in an image format, perform inverse quantization on quantized wavelet coefficients in the three components related to each vertex, and perform inverse transform on the result to obtain the final decoded displacement information.

The decoded texture map (attribute image) may be further processed for conversion of the color space and the color format.

37 FIG. 37 FIG. 200 200 811 812 is a block diagram illustrating a detailed configuration example of decoding deviceaccording to the embodiment. Specifically,is a diagram illustrating an example of a reconstructor that performs subdivision and displacement processing to obtain a decoded mesh frame from the decoded base mesh frame and the decoded displacement information. Decoding deviceincludes subdividerand displacer.

811 The decoded base mesh frame is outputted to subdivider.

811 812 Subdividerperforms subdivision by adding a new vertex between any two connected vertices of the entire mesh frame. This process is repeated several times to include the vertices created in the previous subdivision process, to generate a predefined number of vertices. Each subdivision iteration over the entire three-dimensional mesh frame generates a new level of detail (LoD). The subdivided mesh frame and the decoded displacement information are outputted to displacer.

812 Displacermoves (displaces) each vertex to a new position according to the corresponding displacement information to generate a final decoded three-dimensional mesh frame.

Hereinafter, the subdivision will be described.

38 FIG. is an explanatory diagram illustrating an example of the subdivision.

38 FIG. A base mesh illustrated in (a) inincludes vertices A, B, and C and connection information indicating their connectivity.

38 FIG. 1 In (b) in, a mesh produced by the first subdivision, in other words, a mesh after the first subdivision is illustrated. In the first subdivision, the subdivider generates vertices D, E, and F and connection information indicating their connectivity. This mesh produced by the subdivider will also be referred to as LoDor a first LoD.

Vertex D in the mesh after the first subdivision is a vertex that is generated by subdivision based on vertex A and vertex B. Likewise, vertex F is a vertex that is generated by subdivision based on vertex B and vertex C. Vertex E is a vertex that is generated by subdivision based on vertex A and vertex C.

Note that, as an example, vertex D can be the midpoint of segment AB (in other words, edge AB) connecting vertices A and B, which are used to generate vertex D. Likewise, vertex E can be the midpoint of segment AC. Vertex F can be the midpoint of segment BC.

38 FIG. In (c) in, a mesh produced by the second subdivision, in other words, a mesh after the second subdivision is illustrated. In the second subdivision, the subdivider generates vertices G, H, I, J, K, L, M, N, and O and connection information indicating their connectivity. This mesh produced by the subdivider will also be referred to as LoD2 or a second LoD.

Vertex G in the mesh after the second subdivision is a vertex that is generated by subdivision based on vertex A and vertex D. Likewise, vertex H is a vertex that is generated by subdivision based on vertex A and vertex E. Vertex I is a vertex that is generated by subdivision based on vertex B and vertex D. Vertex J is a vertex that is generated by subdivision based on vertex D and vertex F. Vertex K is a vertex that is generated by subdivision based on vertex E and vertex F. Vertex L is a vertex that is generated by subdivision based on vertex C and vertex E. Vertex M is a vertex that is generated by subdivision based on vertex B and vertex F. Vertex N is a vertex that is generated by subdivision based on vertex C and vertex F. Vertex O is a vertex that is generated by subdivision based on vertex D and vertex E.

Note that, as an example, vertex G can be the midpoint of segment AD (in other words, edge AD) connecting vertices A and D, which are used to generate vertex G. Likewise, vertex H can be the midpoint of segment AE. Vertex I can be the midpoint of segment BD. Vertex J can be the midpoint of segment DF. Vertex K can be the midpoint of segment EF. Vertex L can be the midpoint of segment CE. Vertex M can be the midpoint of segment BF. Vertex N can be the midpoint of segment CF. Vertex O can be the midpoint of segment DE.

39 FIG. 40 FIG. Hereinafter, the displacement of vertices will be described with reference toand.

39 FIG. 40 FIG. is an explanatory diagram illustrating an example of the displacement of vertices in which the vertices are subdivided and then displaced.is an explanatory diagram illustrating an example of the vertices of the original mesh.

39 FIG. A base mesh illustrated in (a) inincludes vertices A, B, C, and Z and connection information indicating their connectivity.

39 FIG. 38 FIG. In (b) in, a mesh produced by the first subdivision, in other words, a mesh after the first subdivision (i.e., a first LoD) is illustrated. In the first subdivision, the subdivider generates vertex S, T, U, X, or Y and connection information indicating their connectivity. Vertex S, T, U, X, or Y is similar to vertices D, E, and F illustrated in (b) in.

39 FIG. 38 FIG. In (c) in, a mesh produced by the second subdivision, in other words, a mesh after the second subdivision (i.e., a second LoD) is illustrated. In the second subdivision, the subdivider generates vertices D, E, F, G, and H and connection information indicating their connectivity. Vertices D, E, F, G, and H are similar to vertices G, H, I, J, K, L, M, N, or O illustrated in (c) in.

39 FIG. 39 FIG. 39 FIG. In (d) in, a mesh including vertices that are subdivided and then displaced is illustrated. Vertices A, B, C, D, E, F, G, H, S, T, U, X, Y, and Z illustrated in (d) inare at positions that are displaced from positions of the respective vertices illustrated in (c) inusing the displacement information.

40 FIG. 100 The original mesh illustrated inis an example of the mesh input into encoding device, that is, a mesh before encoding.

39 FIG. 40 FIG. 1207 100 The mesh illustrated inhas a shape similar to that of the original mesh illustrated in. Since the displacement information is generated by displacement vector calculatorof encoding deviceas information indicating the displacement from the vertices of the base mesh to the vertices of the original mesh, the mesh having the shape similar to that of the original mesh is generated by the reconstruction of the mesh using the displacement information that has been generated in such a manner.

200 39 FIG. Decoding deviceis capable of outputting the mesh illustrated in (d) in.

41 FIG. 42 FIG. Next, the division of a mesh into submeshes will be described with reference toand.

The mesh can be divided into a plurality of portions each of which is smaller than the mesh and can be encoded. When the mesh is divided, the vertices of the mesh can be divided such that sets of coordinates and connectivity of the vertices included in each portion are independently encodable.

41 FIG. 42 FIG. is an explanatory diagram illustrating an example of a mesh.is an explanatory diagram illustrating an example of the division of a mesh into submeshes.

41 FIG. The mesh illustrated inis an original mesh and may also be referred to as a full mesh, in contrast to a submesh.

42 FIG. 41 FIG. 41 FIG. 1 2 1 2 1 2 illustrates how the full mesh illustrated inis divided into two submeshes. For vertices A, B, and C of the full mesh (see), vertex A is duplicated into vertex Aand vertex A, vertex B is duplicated into vertex Band vertex B, and vertex C is duplicated into vertex Cand vertex C. Thus, the two submeshes (i.e., a first submesh and a second submesh) are generated from the full mesh. The first submesh and the second submesh are meshes that are independently decodable.

43 FIG. 44 FIG. 45 FIG. Hereinafter, the packing of displacement information into an image frame will be described with reference to,, and.

43 FIG. 44 FIG. 45 FIG. ,, andare explanatory diagrams illustrating examples of packing the displacement information into an image frame. Note that the image frame can be rephrased as a video frame.

Items of displacement data on vertices are mapped into, for example, components of an image frame in a YUV format (i.e., into Y components (Y Plane), U components (U Plane), and V components (V Plane)), thus being encoded as image frame data. This case will be described below as an example. Note that, as another example, the items of displacement data on vertices may be mapped into components of an image frame in an RGB format (R components, G components, and B components), thus being encoded as the image frame data.

200 Decoding devicecan use an image encoding module to extract the items of displacement data. Each of the items of displacement data may be in the form of an X component, a Y component, or a Z component in a global coordinate system (e.g., a Cartesian coordinate system) or a normal, a tangent, or a bi-tangent component in a local coordinate system. Methods of mapping the displacement data into the image frame include the following methods.

43 FIG. For example, in a first method, the items of displacement data are arranged in a traversing order in the image frame. An example of the packing of the items of displacement data in this case is illustrated in. The items of displacement data are directly mapped onto the image frame according to a predefined traversing order.

43 FIG. Note that the image frame has a fixed height and width, and thus there are cases where the items of displacement data do not fit exactly in the frame. In such a case, the remaining part of the image frame is padded with data for padding (also referred to as Padded data) (see).

44 FIG. 44 FIG. For example, in a second method, the items of displacement data are separated into a plurality of LoDs and mapped into the Y components, U components, and V components of the image frame. An example of the packing of the items of displacement data in this case is illustrated in. Here, the items of displacement data in the image frame for the next LoD start immediately after the items of displacement data for the previous LoD end. As in the first method, in the case where the items of displacement data do not exactly fit in the image frame, the image frame is padded at its end portion (see).

45 FIG. 45 FIG. For example, in a third method, the items of displacement data corresponding to the LoDs are mapped onto the Y components, U components, and V components of the image frame in a manner different from the second method. An example of the packing of the items of displacement data in this case is illustrated in. In this manner, each LoD can be independently decoded. In the third method, interim padding is performed for each LoD's displacement data to provide CTU alignment together with the padding at the end of the video frame (see).

46 FIG. 51 FIG. 46 FIG. 46 FIG. 47 FIG. 46 FIG. 48 FIG. 46 FIG. 47 FIG. 49 FIG. 48 FIG. 50 FIG. 46 FIG. 47 FIG. 51 FIG. 50 FIG. 100 toare explanatory diagrams illustrating textures according to the embodiment. Specifically,is a diagram schematically illustrating textures of a three-dimensional mesh frame inputted to encoding device. More specifically,illustrates an example of a three-dimensional mesh frame containing vertices, their connectivity, and texture coordinates and its associated texture image.is a diagram schematically illustrating a texture image in the case where the texture of the three-dimensional mesh frame illustrated inis overlaid on a UV map.is a diagram schematically illustrating a decoded texture image overlaid on a UV map decoded from the bitstream into which the three-dimensional mesh frame illustrated inandhas been encoded.is a diagram schematically illustrating a three-dimensional mesh frame reconstructed using the texture image illustrated in.is a diagram schematically illustrating another example of a decoded texture image overlaid on a UV map decoded from the bitstream into which the three-dimensional mesh frame illustrated inandhas been encoded.is a diagram schematically illustrating a three-dimensional mesh frame reconstructed using the texture image illustrated in.

46 FIG. 200 100 As illustrated in, it is assumed, for example, that texture A, texture B, and texture C are assigned to three triangles forming the three-dimensional mesh frame. Such a three-dimensional mesh frame is, for example, encoded into a bitstream and transmitted to decoding deviceby encoding device.

200 48 FIG. 49 FIG. In this case, if decoding devicedecodes the bitstream and reconstructs the three-dimensional mesh frame, texture A may not be appropriately assigned and a wrong texture may be assigned instead, as illustrated inand.

200 50 FIG. 51 FIG. Alternatively, in this case, if decoding devicedecodes the bitstream and reconstructs the three-dimensional mesh frame, the reconstructed three-dimensional mesh frame may contain a triangle (face) to which texture A is not appropriately assigned and whose texture is thus missing as illustrated inand.

To solve the artifacts (data error) due to the wrong application of texture to the surface of the reconstructed three-dimensional mesh frame, a UV map for a three-dimensional mesh frame denser than the base mesh frame is generated. An example of the denser three-dimensional mesh frame can be a base mesh frame subdivided after a certain number of subdivision iterations indicated by a first parameter. In practice, higher LoDs do not significantly improve the quality of the reconstructed three-dimensional mesh frame. Consequently, the first parameter can be smaller than the total number of subdivision iterations to be applied to the base mesh frame. This is to provide balance between computation time/resources to generate a UV map and quality. In order to further improve the quality of the reconstructed three-dimensional mesh frame, the vertices of the subdivided three-dimensional mesh frame may be displaced before texture parametrization depending on a second parameter. Hence, the texture parametrization is performed for a three-dimensional mesh frame whose representation is closer to that of the original three-dimensional mesh frame which may eventually improve the quality of the reconstructed three-dimensional mesh frame.

52 FIG. 52 FIG. 35 FIG. 35 FIG. 35 FIG. 100 100 100 100 701 702 703 704 705 706 707 708 709 710 711 712 704 709 is a block diagram illustrating yet another configuration example of encoding deviceaccording to the embodiment. Specifically,is a variation of encoding deviceillustrated in. In the present example, as with encoding deviceillustrated in, encoding deviceincludes decimator, base mesh encoder, base mesh decoder, texture parametrizer, subdivider, displacement vector calculator, displacement information encoder, displacement information decoder, mesh reconstructor, texture converter, video encoder, and multiplexer. On the other hand, unlike the example illustrated in, texture parametrizerin the present example calculates the texture coordinates, based on the decoded (restored) mesh frame outputted from mesh reconstructor.

35 FIG. 704 704 In the example illustrated in, texture parametrizercalculates the texture coordinates, based on the base mesh frame that is not subdivided and whose vertices are not displaced based on the displacement information. In contrast, in the present example, texture parametrizercalculates the texture coordinates, based on the base mesh frame (mesh frame) that is subdivided and whose vertices are displaced based on the displacement information.

53 FIG. 53 FIG. 36 FIG. 36 FIG. 36 FIG. 200 200 200 200 801 802 803 804 805 806 807 803 806 is a block diagram illustrating yet another configuration example of decoding deviceaccording to the embodiment. Specifically,is a variation of decoding deviceillustrated in. In this example, as with decoding deviceillustrated in, decoding deviceincludes demultiplexer, base mesh decoder, texture parametrizer, subdivider, displacement information decoder, mesh reconstructor, and video decoder. On the other hand, unlike the example illustrated in, texture parametrizerin the present example calculates the texture coordinates, based on the decoded mesh frame outputted from mesh reconstructor.

36 FIG. 803 803 In the example illustrated in, texture parametrizercalculates the texture coordinates, based on the base mesh frame that is not subdivided and whose vertices are not displaced based on the displacement information. In contrast, in the present example, texture parametrizercalculates the texture coordinates, based on the decoded base mesh frame (mesh frame) that is subdivided and whose vertices are displaced based on the displacement information.

54 FIG. 54 FIG. 52 FIG. 52 FIG. 100 100 100 713 100 is a block diagram illustrating yet another configuration example of encoding deviceaccording to the embodiment. Specifically,is a variation of encoding deviceillustrated in. In the present example, encoding deviceincludes metadata encoderin addition to the configuration of encoding deviceillustrated in.

704 713 In the present example, texture parametrizercalculates the texture coordinates, based on the decoded mesh frame, and outputs, to metadata encoder, atlas metadata that is auxiliary information for calculating the texture coordinates, based on the decoded mesh frame.

713 712 Metadata encodergenerates a metadata bitstream including the atlas metadata, and outputs the generated metadata bitstream to multiplexer.

712 In the present example, multiplexergenerates and outputs a compressed bitstream including: the metadata bitstream; the base mesh bitstream; the displacement information bitstream; and the attribute information bitstream.

100 100 52 FIG. As described above, encoding devicein the example illustrated indoes not transmit the atlas metadata, whereas encoding devicein the present example transmits the atlas metadata.

55 FIG. 55 FIG. 53 FIG. 53 FIG. 200 200 200 808 200 is a block diagram illustrating yet another configuration example of decoding deviceaccording to the embodiment. Specifically,is a variation of decoding deviceillustrated in. In the present example, decoding deviceincludes metadata decoderin addition to the configuration of decoding deviceillustrated in.

801 801 808 802 805 807 In the present example, demultiplexerseparates the compressed bitstream into a metadata bitstream, a base mesh bitstream, a displacement information bitstream, and an attribute information bitstream. Demultiplexeroutputs the metadata bitstream to metadata decoder, outputs the base mesh bitstream to base mesh decoder, outputs the displacement information bitstream to displacement information decoder, and outputs the attribute information bitstream to video decoder.

808 803 Metadata decoderdecodes the atlas metadata from the metadata bitstream, and outputs the decoded atlas metadata to texture parametrizer.

803 803 804 200 803 Note that the present example has illustrated the case where the texture coordinates are calculated using the atlas metadata; however, if the texture coordinates are directly encoded into the metadata bitstream, texture parametrizerneed not calculate the texture coordinates. For example, texture parametrizermay output the decoded texture coordinates and the decoded base mesh frame to subdivider. In this case, decoding deviceneed not include texture parametrizer.

56 FIG. 56 FIG. 200 is a flowchart illustrating an example of a texture coordinate derivation process according to the embodiment. For example, decoding deviceperforms the processes illustrated in the flowchart in.

200 301 First, decoding devicedecodes one or more first vertices and a first parameter from an encoded bitstream (S). The one or more first vertices are part of a three-dimensional mesh frame. For example, the one or more first vertices are vertices of a base mesh frame. For example, the three-dimensional mesh frame is a submesh frame. For example, the first parameter is signaled in a frame header. For example, the first parameter is signaled in a sequence header. For example, the first parameter indicates the total number of subdivision iterations to be applied to the one or more first vertices.

200 302 200 Next, decoding devicedecodes one or more second vertices using the one or more first vertices and the first parameter (S). The position of each second vertex is derived using one or more positions of the one or more first vertices and the first parameter. The one or more first vertices and the one or more second vertices are part of the same three-dimensional mesh frame. For example, the one or more second vertices are vertices of a subdivided mesh frame. For example, decoding devicemay decode a second parameter. For example, the second parameter indicates whether the one or more second vertices are to be displaced before the texture coordinates are derived. For example, the second parameter is signaled in a frame header. For example, the second parameter is signaled in a sequence header.

200 303 200 Next, decoding devicederives texture coordinates using one or more positions of the one or more second vertices (S). For example, decoding devicedecodes (calculates) the texture coordinates using a refined mesh frame (for example, a mesh frame that is subdivided and whose vertices are displaced based on the displacement information).

57 FIG. is a flowchart illustrating another example of a texture coordinate derivation process according to the embodiment.

200 401 First, decoding devicedecodes one or more first vertices, a first parameter, and a second parameter from an encoded bitstream (S). For example, the one or more first vertices are part of a three-dimensional mesh frame. For example, the second parameter is of boolean data type.

200 402 Next, decoding devicedecodes one or more second vertices using one or more first vertices and the first parameter (S). For example, the position of each second vertex is derived using one or more positions of the one or more first vertices and the first parameter. For example, the one or more first vertices and the one or more second vertices are part of the same three-dimensional mesh frame.

200 403 Next, decoding devicedetermines the value of the second parameter (S).

403 200 404 If the second parameter is true (Yes in S), decoding devicedisplaces the one or more second vertices (S).

403 404 200 405 403 200 403 200 If the second parameter is not true (No in S) or after step S, decoding devicederives the texture coordinates using one or more positions of the one or more second vertices (S). For example, in the case of Yes in step S, decoding devicecalculates texture coordinates using the mesh frame whose one or more second vertices have been displaced, whereas in the case of No in step S, decoding devicecalculates texture coordinates using the mesh frame whose one or more second vertices are not displaced.

58 FIG. is a diagram illustrating an example of a layout of syntax parameters according to the embodiment.

For example, the first parameter and the second parameter are signaled in a sequence header, a frame header, or a submesh frame header. The sequence header may be referred to by one or more frames. The frame header may be referred to by one or more submesh frames.

59 FIG. 59 FIG. illustrates an example of a syntax for signaling the first parameter according to the embodiment. Specifically,illustrates an example of a syntax for signaling the first parameter that indicates a total number of subdivision iterations before texture parametrization. Note that the first parameter may be signaled as a differential value from the total number of subdivision iterations for reconstruction of the submesh frame.

subdivision_enabled_flag is a flag indicating whether to perform subdivision.

For example, subdivision_enabled_flag equal to 1 indicates that lod_for_texture_parametrization may be present in a patch. On the other hand, subdivision_enabled_flag equal to 0 indicates that lod_for_texture_parametrization is not present in a patch.

lod_for_texture_parametrization indicates the total number of subdivision iterations used for the subdivision before texture parametrization in a patch. When lod_for_texture_parametrization is not present, its value is inferred to be equal to 0. lod_for_texture_parametrization is an example of the first count information and the second count information.

60 FIG. 60 FIG. illustrates an example of a syntax for signaling the second parameter according to the embodiment. Specifically,illustrates an example of a syntax for signaling the second parameter that indicates whether to displace vertices before texture parametrization.

displace_vertices_before_texture_parametrization_flag is information indicating whether to displace vertices. displace_vertices_before_texture_parametrization_flag is an example of the flag information.

For example, displace_vertices_before_texture_parametrization_flag equal to 1 indicates that the vertices after being subjected to subdivision iterations the total number of which is indicated by lod_for_texture_parametrization are displaced before texture parametrization is applied in a patch.

When displace_vertices_before_texture_parametrization_flag is not present, its value is inferred to be equal to 0.

200 200 200 If the texture coordinates are signaled in the bitstream, decoding devicefirst decodes the base mesh frame and subdivides the base mesh frame at the total number of subdivision iterations indicated by the first parameter to derive the refined mesh frame. The texture coordinates corresponding to the refined mesh frame may be decoded by a base mesh codec or may be decoded by any decoding device other than decoding device(for example, other than decoding deviceaccording to the present disclosure), or the texture coordinates decoded by the base mesh codec may be subdivided.

200 200 Next, decoding devicechecks whether the second parameter exists in the bitstream, and displaces vertices of the refined mesh frame. Decoding deviceapplies displacement to the refined mesh frame depending on the decoded flag.

Lastly, the vertices of the refined mesh frame are paired up with the decoded texture coordinates. The pairing of the vertices and the texture coordinates need not be strict one-to-one mapping. That is to say, one vertex may have two or more sets of texture coordinates, and two or more vertices may have one set of texture coordinates (stated differently, the same texture coordinates).

200 With such a configuration as described above, the present disclosure can improve the quality of the three-dimensional mesh frame reconstructed. Note that the present disclosure is not limited to the tools (for example, orthoAtlas or UVAtlas) used for generating texture coordinates (UV coordinates). Also, the present disclosure can work in both the case of the UV map (texture image) being signaled in the bitstream and the case of high-level syntax parameters used by decoding devicefor generating the UV map.

200 Decoding devicecan be implemented by combining at least part of other aspects of the present disclosure. In addition, the present disclosure may be implemented by combining, with other aspects, part of the processes indicated in any of the flowcharts according to one aspect, part of the configuration of any of the devices, part of syntaxes, etc.

200 100 The above process of decoding devicemay be performed similarly in encoding deviceas well. In addition, not all the constituent elements in the present disclosure are always necessary, and only part of the constituent elements of the present disclosure may be included.

100 151 152 151 151 As described above, for example, encoding deviceincludes: circuit; and memoryconnected to circuit, in which, in operation, circuit: encodes one or more first vertices and a first parameter from an encoded bitstream, the one or more first vertices being part of a three-dimensional mesh frame; encodes one or more second vertices using the one or more first vertices and the first parameter, a position of each of the one or more second vertices being derived using one or more positions of the one or more first vertices and the first parameter, the one or more first vertices and the one or more second vertices being part of the same three-dimensional mesh frame; and derives a texture coordinate using the one or more second vertices, the texture coordinate being derived using one or more positions of the one or more second vertices.

200 251 252 251 251 In addition, for example, decoding deviceincludes: circuit; and memoryconnected to circuit, in which, in operation, circuit: decodes one or more first vertices and a first parameter from an encoded bitstream, the one or more first vertices being part of a three-dimensional mesh frame; decodes one or more second vertices using the one or more first vertices and the first parameter, a position of each of the one or more second vertices being derived using one or more positions of the one or more first vertices and the first parameter, the one or more first vertices and the one or more second vertices being part of the same three-dimensional mesh frame; and derives a texture coordinate using the one or more second vertices, the texture coordinate being derived using one or more positions of the one or more second vertices.

In addition, for example, an encoding method includes: encoding one or more first vertices and a first parameter from an encoded bitstream, the one or more first vertices being part of a 3D mesh; encoding one or more second vertices using the one or more first vertices and the first parameter, a position of each of the one or more second vertices being derived using one or more positions of the one or more first vertices and the first parameter, the one or more first vertices and the one or more second vertices being part of the same three-dimensional mesh frame; and deriving a texture coordinate using the one or more second vertices, the texture coordinate being derived using one or more positions of the one or more second vertices.

In addition, for example, a decoding method includes: decoding one or more first vertices and a first parameter from an encoded bitstream, the one or more first vertices being part of a three-dimensional mesh frame; decoding one or more second vertices using the one or more first vertices and the first parameter, a position of each of the one or more second vertices being derived using one or more positions of the one or more first vertices and the first parameter, the one or more first vertices and the one or more second vertices being part of the same three-dimensional mesh frame; and deriving a texture coordinate using the one or more second vertices, the texture coordinate being derived using one or more positions of the one or more second vertices.

In addition, for example, the three-dimensional mesh frame is a submesh.

In addition, for example, in the decoding, a second parameter is decoded, and the second parameter indicates whether to displace the one or more second vertices before the derivation of the texture coordinates.

In addition, for example, each of the one or more first vertices is a base mesh (specifically, a vertex included in a base mesh).

In addition, for example, each of the one or more second vertices is a subdivided mesh (specifically, a vertex included in a submesh).

In addition, for example, the first parameter is signaled in a frame header.

In addition, for example, the second parameter is signaled in a frame header.

In addition, for example, the first parameter is signaled in a sequence header.

In addition, for example, the second parameter is signaled in a sequence header.

In addition, for example, the first parameter indicates the total number of subdivision iterations to be applied to the one or more first vertices.

In the encoding technique for multimedia data, there is a demand for new methods for improving the encoding efficiency and the image quality and for reducing the circuit size.

Each of one or more embodiments, some of the constituent elements, and each of the methods according to the present disclosure enables, for example, at least one of improvement in encoding efficiency, improvement in image quality, reduction in encoding/decoding processing amount, reduction in circuit size, improvement in encoding/decoding processing speed, or the like. Alternatively, each embodiment according to the present disclosure partially or entirely enables any of an element such as a filter, a block, a size, a motion vector, a reference picture, and a reference block, or an arithmetic operation to be appropriately selected in encoding and decoding. The present disclosure may include a disclosure relating to a configuration and a method that can provide an advantage other than the advantages described above. Examples of such a configuration and a method include a configuration or a method that improves the encoding efficiency while suppressing an increase in the processing amount.

Additional values and advantages of aspects of the present disclosure will be apparent from the specification and the drawings. The values and/or advantages can be provided by each of the various embodiments and features described in the specification and the drawings, and not all the embodiments and features in the specification and the drawings are necessary to provide one or more of such values and/or advantages.

These general or specific aspects can be implemented by using a system, an integrated circuit, a computer program, a computer-readable recording medium such as a CD-ROM, or any combination of systems, methods, integrated circuits, computer programs, or computer-readable recording media.

61 FIG. 24 FIG. 61 FIG. 100 151 152 151 151 is a flowchart illustrating an example of a basic encoding process according to the present embodiment. For example, encoding deviceillustrated inincludes circuitand memoryconnected to circuit, and circuit, in operation, performs the encoding process illustrated in.

100 501 First, based on positions of a plurality of second vertices generated based on positions of a plurality of first vertices included in a first three-dimensional mesh frame, encoding devicecalculates texture coordinates indicating positions of the plurality of second vertices in a two-dimensional coordinate system (S).

100 502 100 Next, encoding deviceencodes, into a bitstream, (i) position information indicating the positions of the plurality of first vertices and (ii) a texture image that is in accordance with the texture coordinates (S). That is to say, encoding devicegenerates a bitstream including the position information and the texture image.

The first three-dimensional mesh frame is the above-described base mesh frame, for example. The plurality of first vertices are, for example, a plurality of three-dimensional points included in the base mesh frame. The second vertices are, for example, three-dimensional points generated as a result of subdivision of the base mesh frame. The two-dimensional coordinates are, for example, coordinates in the texture image. The texture image is, for example, the attribute image (texture data) described above.

The plurality of second vertices are generated as a result of subdivision of the first three-dimensional mesh frame, for example. This makes it possible to generate a mesh frame denser than the first three-dimensional mesh frame. By calculating texture coordinates based on the mesh frame generated in such a manner, that is, by determining the texture of the mesh frame, it is possible to determine the texture coordinates more finely than in the case of calculating the texture coordinates based on the plurality of first vertices. Accordingly, defects such as application of a wrong texture or no texture to the first three-dimensional mesh frame by a decoding process or the like can be inhibited.

100 In addition, for example, encoding devicegenerates the texture image based on the texture coordinates.

With this, only the texture image related to the calculated texture coordinates is encoded into the bitstream. Accordingly, the code amount of the bitstream is reduced.

100 In addition, for example, encoding devicefurther generates the plurality of second vertices by subdividing the first three-dimensional mesh frame.

This makes it possible to determine the texture coordinates more finely than in the case of calculating the texture coordinates based on the plurality of first vertices.

100 In addition, for example, encoding devicefurther encodes, into the bitstream, first count information indicating a total number of times the first three-dimensional mesh frame is subdivided to calculate the texture coordinates.

The first count information is the above-described first parameter, for example.

200 This makes it possible to perform subdivisions the same number of times in encoding and decoding. Accordingly, the quality of the three-dimensional mesh frame reconstructed by decoding devicecan be improved.

100 In addition, for example, encoding devicefurther encodes, into the bitstream, second count information indicating a total number of times the first three-dimensional mesh frame is subdivided to generate a second three-dimensional mesh frame from the first three-dimensional mesh frame.

The second three-dimensional mesh frame is the above-described original mesh frame, for example. The second count information is the above-described first parameter, for example.

Note that in the above example, the total number of times the first three-dimensional mesh frame is subdivided to calculate texture coordinates and the total number of times the first three-dimensional mesh frame is subdivided to generate the second three-dimensional mesh frame from the first three-dimensional mesh frame are the same; therefore, the first parameter indicates both the first count information and the second count information. If these numbers are different, parameters indicating these numbers may be included in the bitstream.

100 200 200 With this, for example, even when a difference exists between the total number of times the first three-dimensional mesh frame is subdivided to calculate texture coordinates and the total number of times the first three-dimensional mesh frame is subdivided to generate the second three-dimensional mesh frame from the first three-dimensional mesh frame, encoding deviceand decoding devicecan perform subdivisions the same number of times. Accordingly, the quality of the three-dimensional mesh frame reconstructed by decoding devicecan be improved.

100 In addition, for example, encoding devicefurther: displaces the plurality of second vertices; and when calculating the texture coordinates, calculates the texture coordinates based on the positions of the plurality of second vertices after displacement.

100 For example, encoding deviceencodes, into a bitstream, the above-described displacement information as information indicating the amount of displacement of the vertices.

100 200 With this, even when vertices are displaced and then position information indicating the positions of the displaced vertices is encoded, encoding deviceand decoding devicecan calculate texture coordinates using vertices of the same positions.

100 In addition, for example, encoding deviceencodes, into the bitstream, flag information indicating whether to displace the plurality of second vertices.

The flag information is the above-described second parameter, for example.

200 This makes it possible for decoding deviceto determine whether to displace vertices based on the flag information.

62 FIG. 25 FIG. 62 FIG. 200 251 252 251 251 is a flowchart illustrating an example of a basic decoding process according to the present embodiment. For example, decoding deviceillustrated inincludes circuitand memoryconnected to circuit, and circuit, in operation, performs the decoding process illustrated in.

200 601 200 First, decoding devicedecodes, from a bitstream, (i) position information indicating positions of a plurality of first vertices included in a first three-dimensional mesh frame and (ii) a texture image (S). That is to say, decoding deviceobtains the position information and the texture image from the bitstream.

200 602 200 Next, by using positions of a plurality of second vertices generated from the position information, decoding devicecalculates texture coordinates indicating positions of the plurality of second vertices in the texture image (S). Decoding devicereconstructs a three-dimensional mesh frame by using the position information, the texture image, and the texture coordinates.

The plurality of second vertices are generated as a result of subdivision of the first three-dimensional mesh frame, for example. This makes it possible to generate a mesh frame denser than the first three-dimensional mesh frame. By calculating texture coordinates based on the mesh frame generated in such a manner, that is, by determining the texture of the mesh frame, it is possible to determine the texture coordinates more finely than in the case of calculating the texture coordinates based on the plurality of first vertices. Accordingly, defects such as application of a wrong texture or no texture to the first three-dimensional mesh frame by a decoding process or the like can be inhibited.

200 In addition, for example, decoding devicefurther generates the plurality of second vertices by subdividing the first three-dimensional mesh frame.

This makes it possible to determine the texture coordinates more finely than in the case of calculating the texture coordinates based on the plurality of first vertices.

200 In addition, for example, decoding devicefurther: decodes, from the bitstream, first count information indicating a total number of times the first three-dimensional mesh frame is subdivided to calculate the texture coordinates; and when calculating the texture coordinates, calculates the texture coordinates using the first count information.

200 This makes it possible to perform subdivisions the same number of times in encoding and decoding. Accordingly, the quality of the three-dimensional mesh frame reconstructed by decoding devicecan be improved.

200 In addition, for example, decoding devicefurther: decodes, from the bitstream, second count information indicating a total number of times the first three-dimensional mesh frame is subdivided to generate a second three-dimensional mesh frame from the first three-dimensional mesh frame; and generates the second three-dimensional mesh frame from the first three-dimensional mesh frame by using the texture coordinates and the second count information.

100 200 200 With this, for example, even when a difference exists between the total number of times the first three-dimensional mesh frame is subdivided to calculate texture coordinates and the total number of times the first three-dimensional mesh frame is subdivided to generate the second three-dimensional mesh frame from the first three-dimensional mesh frame, encoding deviceand decoding devicecan perform subdivisions the same number of times. Accordingly, the quality of the three-dimensional mesh frame reconstructed by decoding devicecan be improved.

200 In addition, for example, decoding devicefurther: displaces the plurality of second vertices; and when calculating the texture coordinates, calculates the texture coordinates based on the positions of the plurality of second vertices after displacement.

100 200 With this, even when vertices are displaced and then position information indicating the positions of the displaced vertices is encoded, encoding deviceand decoding devicecan calculate texture coordinates using vertices of the same positions.

200 In addition, for example, decoding devicedecodes, from the bitstream, flag information indicating whether to displace the plurality of second vertices.

200 This makes it possible for decoding deviceto determine whether to displace vertices based on the flag information.

100 200 100 200 Although aspects of encoding deviceand decoding devicehave thus far been described according to the embodiment, the aspects of encoding deviceand decoding deviceare not limited to the embodiment. Modifications that may be conceived by a person skilled in the art may be applied to the embodiment, and a plurality of constituent elements in the embodiment may be combined in any manner.

For example, processing performed by a specific constituent element in the embodiment may be performed by a different constituent element instead of the specific constituent element. Moreover, the order of processes may be changed or processes may be performed in parallel.

200 Moreover, as stated above, it is possible to implement, as an integrated circuit, at least part of the plurality of constituent elements in the present disclosure. At least some of the processes in the present disclosure may be used as an encoding method or a decoding method. A program for causing a computer to execute the encoding method or the decoding method may be used. Furthermore, a non-transitory computer-readable recording medium on which the program is recorded may be used. In addition, a bitstream for causing decoding deviceto perform a decoding process may be used.

Moreover, at least some of the plurality of constituent elements and the processes in the present disclosure may be used as a transmitting device, a receiving device, a transmitting method, and a receiving method. A program for causing a computer to execute the transmitting method or the receiving method may be used. Furthermore, a non-transitory computer-readable recording medium on which the program is recorded may be used.

The present disclosure is useful in, for example, an encoding device, a decoding device, a transmitting device, a receiving device, and the like related to a three-dimensional mesh and can be applied to a computer graphics system, a three-dimensional data display system, and the like.